Both AMD and Nvidia GPUs work well. There is mainly a philosophy difference where AMD GPUs work particularly well with open source drivers whereas Nvidia still mostly depends on its proprietary drivers (though they work fine on Linux too).
Phoronix is a reputable website when it comes to benchmarking on Linux. Here is a previous benchmark with Nvidia GPUs, as an example:
Of note: when people complain about nvidia on Linux, you need to determine whether they complain about open source or proprietary drivers.
I have been running Nvidia GPUs on Linux for years and have had no issue with the proprietary drivers, both for an old and recent GPU. Of course YMMV.
Edit: my personal recommendation though would be to stick with AMD which offers more memory and bandwidth compared to similarly priced Nvidia GPUs (Nvidia uses 8GB for many of its GPUs which is quire disappointing these days). And with open source drivers it may be easier to get issues fixed and find support.