I tend to feel the modern Stern games are just too complicated. I enjoy the 90s Williams games the most, but find that I play the early SS and EMs quite a bit more lately. I tried to build a diverse collection of all years, types and manufacturers. Beyond that I do have other EM arcade games and a big ball bowler to try and round things out.
Seriously, there are days where I feel that I could be completely content with having just all EMs.