I feel like MKDS isn't very technical, it's hard to play and to get good at, yes, but it lacks technics in my opinion. I also don't agree with Batman, you can be good at a game and still find it technical, while you can suck at MK7 and MK8DX and still find them piss easy in terms of technics. I think the most technical MK would be the one where it is the hardest to explain how to make a good run, and MKDS mainly relies on PRB, which is basically just chaining drifts very fast.
The 3 which stick out for me are SMK (because of all the NBTs, the fact that you might need to mod your controller, and the NBT/Non-NBT, PAL/NTSC, and Glitch/No Glitch categories), MKSC (because of ZZMTs, ticking, the fact that you also might need to mod your controller, all the Non-SC rules and thus all the SCs) and MKDD (because of 50Hz/60Hz, A-tech, L-tech, R-tech, T-tech...

). I voted MKSC though.