I have not used the RSX, but I have two RS Gen V2's. I found them very easy to use and the Hotwire software (once you work through some compatibility with your personal devices) is very simple to make changes. I also like that I can simply carry my phone to the track to make those adjustments.
The ESC's are more on the expensive side but I've not had an issue with one yet. I looked at them originally for the BEC support. I had a Savox servo which was known to pull a lot of amps and the non-spec RS Gen V2 had very good amp support.
The other reason I went with Tekin is that they have representatives on this forum, supporting their products. While it's not necessarily as quick as going through their official support, it's nice to see them out in the public providing support. Since I didn't have issues that were critical, using this forum to get assistance with some phone/laptop compatibility issues with Hotwire worked like a charm.