SpaceOtter

For me, Science Mode is missing, but not as much as the thermal mechanics... For me, landing in Eve without it seems a bit like cheating (not judging, though).

As a complete enthusiast of career mode on KSP 1 and problably adventure mode on KSP2, my biggest concern would be the first update (science). That one would take us where we left on the first game. After that, I wouldn't mind for a big gap between updates.