Speedrum

I don't really like MPC layout but in general Speedrum is really good drum sampler. I hear exactly what I'm expecting to hear because some other similar samplers produce sound which is a bit different from the original wavs. I love built-in compressor for the same reason - I'm getting the sound I need very quickly and I don't have to route Reaper's outs to separate compressor anymore. One of my reasons to buy it is the simple xml format for banks because I prefer to generate banks with script.
UI is perfectly scaling on 4K monitor, I had to get rid of some old VST because of HIDPI issues.
Support was very helpful with my questions about xml and MIDI mapping.