Do some searches here on each model and you'll find quite a bit. I personally run the PSR-300, among other scanners, and that's what I suggest people get who want an analog trunk tracker. I got mine when ScannerMaster was running a sale for $149 with free shipping. It came with an AC power adapter as well.
Some people say if you want features, go with Uniden. If you want performance, go with GRE. That's been my experience. Some of the Unidens can be completely controlled via a PC, and have some interesting features. I have not personally used the 346XT, but have had a 396T here and was not impressed with its performance. Although it was programmed the same as my scanners it was not picking stuff up that mine were and they were all sitting next to each other.
I have both the BC346XT and the PSR-300. Both have strengths and weaknesses. The BC346XT has more channels and features, but the PSR-300 receives distant signals better. However, because the PSR-300 has a more sensitive receiver, it picks up more interference at times than the BC346XT. To tell you the truth, I like them both, and will use each radio for a specific task or location. As mentioned above, read through the e-Ham reviews, and the Wiki for each radio, to make an informed decision. Good luck!