Generally the 536 are the better scanner but also more expensive. It's user interface are much better and there's lots of supportive programs for it. No RF issues and have a better receive sensitivity than the TRX.
TRX have its programming files encrypted so there's no other program software than EZ-Scan. It's keypad are terrible so making changes directly on the scanner are difficult. It doesn't help that the selector knob goes backwards when choosing between characters to enter. It doesn't use any calibration for its squelch so there's one optimum setting for VHF and another setting needed for UHF. I've only noticed overload issues on VHF.
TRX have some things going for it like excellent audio quality from its speaker and audio AGC. It can record audio files individually for a frequency or Talk Group and it has a wildcard ID to allow you to set specific credentials for any unknown TG's. TRX's digital decode quality are superior to 536. You get both DMR and NXDN included and do not need to spend those extra $110.
There's must be lots of second hand TRX and 536 as people buy Uniden SDS scanners to handle simulcast systems so I would look at that, and buy both scanners as they both excel at different things and if they are second hand ones they can be sold for close to the same that you paid for them.
/Ubbe