Replace Windows 10 Start Menu With These Alternatives
The new Start Menu in Windows 10 is definitely one of the biggest updates over previous versions; right behind Cortana. It's sleek, highly customizable, and comes with cool live tiles that show real-time information from apps.
As powerful as it is, I personally don't like the Start menu in Windows 10; it just looks as if it's been pummeled by a rainbow. To make it easier, I tried to get rid of the entire live tile section, but that was the wrong call, since I still need it to pin important apps. Luckily, I found a third-party Windows 10 Start Menu replacement that allowed me to customize the Start menu exactly the way I wanted.
If you are one of those classics who prefer the elegant and simple design of the Windows 7 era, then I know suitable alternatives that will help you. Below you will find some of the best Windows 10 Start Menu alternatives that will allow you to completely change the look and feel of the Start menu and even add extra features you didn't even know you had.
It's a free app, but IObit advertises their other programs on installation and in the new start menu on first use. It has a paid version with automatic updates, but you don't have to buy it. Start Menu 8 has two start menu styles, one is based on the style of Windows 7 and the other is a bit flat, similar to the Windows 8 menu.
It has over a dozen built-in start menu buttons that are actually very high quality. Like other apps, the Start menu is fully customizable and you can add items to remove and resize icons as you see fit.
Open shell (classic shell)
Classic Shell has been the main alternative to the standard Windows Start Menu for many years. Unfortunately, the classic shell developer had to leave the project so he made it open source. Open Shell is the same Classic Shell app, but is updated by volunteer developers to stay up to date with Windows 10 updates. The main purpose of Open Shell is to replace the Windows 10 Start Menu with the Windows 7 Start Menu, which can be optionally customize with skins.
When you first launch the app, you have to select the start menu style (one or two columns) and then apply the skin you prefer (try Metallic, it's really good). This is enough to get a new Start menu, simple and functional. However, if you want to further customize, then you can do a lot more.

The General Options and Customize Start Menu tabs will help you customize which buttons to display on the Start menu and which menu to open when you right-click the Start menu or press the Windows key. You can also replace the start menu button with your own image and resize it.

When you're ready to take full control of the Start Menu, check the "Show all settings" box at the top. This opens up another dozen tabs for fully customizing the Start menu. You can control the start menu button, change main menu items, choose right-click menu behavior, change menu design and animation, switch language, control search box behavior, and more.

I may be a little biased, having been a Classic Shell user for over 5 years, but in my opinion, this is the most customizable Start Menu alternative, and it's also completely free.
StartIsBack
StartIsBack definitely has a much better user interface than Open Shell, but it's a little less customizable. This Windows Start Menu alternative is designed for both the Start Menu and the Windows Taskbar. Any changes you make will affect both the Start Menu and Taskbar.

It comes with 3 start menu styles which are mostly inspired by the Windows 7 start menu. You can also select a custom image for the start menu button or use the Windows 7 button provided by the application. More importantly, it allows you to change the color of the taskbar and start menu to any color you like.

If you go to the Customize Behavior section, you'll find plenty of options to customize how you interact with the Start menu. You can choose which apps and items appear on the Start menu by default, and change how the power button behaves. In addition, its search feature allows you to send a query to Cortana if nothing is found in programs and folders.

StartIsBack is a paid app that replaces the Windows 10 Start Menu and you can get a lifetime license for $3.99 for a single PC. Although it has a 30 day trial which contains all the features you can appreciate.
Start10
Start10 takes a slightly different approach to styling the Start menu. Instead of exactly copying the style of Windows 7, it simplifies the style of the Windows 10 Start Menu. There is a Windows 7-inspired style that uses the basic structure of Windows 7, but incorporates well the Windows 10 icon styles and app selection. As well as a modern style that works the same but uses the background of the Windows 10 Start menu.

A more interesting feature of Start10 is the ability to add cool themes and images as the background of the start menu and taskbar. You can even upload your own photo and apply it as your Start menu background. Like other Start Menu apps, Start10 also lets you customize icon size, pin apps, show recent apps, and add programs as links or menus.

If you go to the "Manage" section of the app, you'll find plenty of options to control how you open the Start10 menu. For example, you can decide whether the Windows button or clicking the Start menu icon will open the Start10 menu or the default Start menu in Windows 10. This can be extremely useful if you intend to use the Start10 menu and start menu by default.

Start10 is also a premium app and you will have to pay $3.74 to get a lifetime license. Although it is possible to use a fully functional 30-day trial before purchase (requires email registration).
If you want to make your Windows 10 menu even more functional than Start Menu X might intrigue you. Instead of simplifying the Windows 7-style Start Menu, Start Menu X revamps the Start menu for quick access to apps and folder data. Basically, it turns any Windows folder or setting into a searchable menu that shows all of its contents on hover.
You can access folders and their items directly from the start menu and even access subfolders. The app uses the Live Tiles section of the Start menu to list all the sub-items of folders and apps, and you can also customize the location of each item right from here.

Another cool feature of the Start X menu is the ability to set timer-based power options such as reboot, shutdown, logout, etc. You can set a specific timer and your computer will use one of the power options when the time will come. up. This can be extremely useful for shutting down your PC when you're away if a program needs to complete a task.

Like other applications, it has several skins and styles to customize the appearance of the start menu. Most of the Start Menu X features are available in the free version, but the One-Click-Launch feature is only available in the $9.99 paid version.
More Start Menu Alternatives in Windows 10
I consider the above to be the best Windows 10 Start Menu alternative. Each of them has its own unique features, so it is worth choosing them depending on your preferences. However, there are other apps that can work as an alternative to the Start menu in Windows 10. Although some of them are no longer updated, so there is a chance that they might break in the future. Others don't offer enough interesting features for me to draw attention to them.
I'm still listing them here as some of you may find them useful depending on your needs.
ViStart
A very simple Windows 10 start menu alternative to get a Windows 7 or Windows 8 style start menu. I must say that the Windows 7 theme start menu looks exactly like the real Windows 7 start menu , and Windows 8 also copies menu styles perfectly. You can also download additional skins if you don't like the current ones. ViStart is also completely free and open source.

This app works similar to the default Windows 10 Start menu, but has its own interface and limitations. Start Menu Recovery comes with a tile feature that supports up to 64 tiles that you can scroll through. Tiles is also not limited to apps and settings, you can add just about any file; including media files and websites. Important settings and folders are listed on the left, and you can use the All Apps button to view all installed apps on your PC.

Unfortunately, the size of the Start menu is very small and it seems impossible to resize it. This makes the start menu very difficult to navigate, as the headings take up a lot of space.
Final Thoughts
I personally use Open Shell because I love its two-column start menu and the customization it offers is mind blowing. In case you don't know, Microsoft is also working on simplifying the Start Menu and many of the changes have already been pushed to the Insider Build. If you like these changes, then soon you may not even need a Windows 10 Start Menu alternative.
Then learn how you can tweak Windows 10 for better performance.