Windows 11 or Windows 10
Windows 11 has been available to Windows Insiders since launch. Being a Windows Insider means that you switch on more Microsoft telemetry data and you test new versions of Windows before they are released to everyone. The good news is you get the very latest Windows that it's possible to have. The bad news is that the Dev Channel and Beta Channel have buggy versions of Windows.
If you have a PC that you use every day and is important then you should not put it on the Insider programme. You should use a different machine to avoid your main device being unusable. The problem with that approach is that you are not testing in a real scenario. From that perspective using another PC that is not used for normal work is going to be mis-leading as a test machine. If you just want to see what the next Windows is going to be like then using a non-production machine, or a virtual machine, is fine. To do real testing you need your production machine updated. If you really go for it then make sure you have a good backup strategy. Make sure the backup can be restored.
I did switch my PC to "dev" just to look at Windows 11. However, I got nervous and reverted back to Windows 10. The hardware requirements of Windows 11 are that you must have the TPM 2.0 security chip. As a result of that decision many people won't be able to use Windows 10 at all. In practice this means Windows 10 will carry on until 2025. Ten years after it's first release. By then TPM 2.0 will have been part of every new build PC for years.
TPM security is a good thing. Making operating systems more secure and safer for most users. There have been mutterings from people who build their own PCs and from people with relatively recent PCs that don't have TPM 2.0. Microsoft haven't made much of this as a security improvement.
If you want Windows 11 then you can get it now via the Windows Insider programme, as long as your PC meets the requirements. I have tried it and it's looking good. Windows 10 isn't going away and there are many updates to come.