Both the Benchmark LA4 and Bryston BP-17^3 are designed to be reference-oriented devices. So things like frequency response, etc. will be very similar. The noise floor on the LA4 is lower. The BP-17^3 has more inputs and outputs, plus a headphone jack and the option for DAC or phono modules. They're both excellent options.
The BP-17^3 has been discontinued, so you will likely not find it available new. But it does mean you may be able to find a used or demo unit at a better price (I have a demo unit available). The BP-19 replaced the BP-17^3 and still fits in your budget. The BR-20 is a little above your budget.