Honestly just use Ghidra. It has it's quirks but it's pretty good. And open source. If it's good enough for the NSA it's probably good enough for recreational use.

If Ghidra is made by NSA, does it mean that it can have backdoors for non-US users?

The code is open source and has been looked at by several people over the years. It would be quite hard for the NSA to sneak in a backdoor but it is never out of the question. However, the risk is so extremely minuscule when compared to other alternatives since they are not even open source.

Binja decompiler is more-or-less fine. Its not as mature as IDA or Ghidra but its not a bad decompiler.

Though for me the big selling point on Binja is the Intermediate Languages (ILs). HIgh-level IL is the decompiler but you also get Low-level and Medium-level ILs as steps between assembly and source. If the decompiler is a bit funky you can look at the ILs to get a better idea of what is happening. the ILs are also just much nicer to read than plain assembly so I tend to use them a lot.

Its a feature that isn't really matched on any other platform. Ghidra and IDA both have a single IL that is more machine readable compared to Binja's human-readable ones.

IDA Free has essentially all the features of Pro nowadays, if you're only looking to do x86_64 on Windows/Linux.

https://hex-rays.com/ida-free/

The only thing you lose out on is Python scripting, which is kind of big, but for a free tool you really can't complain.

You probably want to use both IDA and Ghidra since they have different strengths/weaknesses and community plugins.