For better ride, 15’s usually. Tires built for 15’s are almost always load range C. Most tires for 17’s in the larger sizes are load range E which is more for heavy trucks like 2500s. Not all E tires ride bad, but most do.
however, on 17’s, if you keep it to smaller 265 profile tires, many of them have passenger rating options, which can carry more load than a load c, but have slightly weaker/thinner sidewalls so they ride better. For someone not going off-road it’s a solid option. So for example, a 265/70R17, is 31.6 x 10.50. You can get plenty of tires in that size as an SL (standard load/passenger) rating which will ride well.
The bigger issue for me is finding 17” rims that look decent to me on a YJ. Most of them look kind of large. 17’s are not a bad way to go though, but on a street rig I would definitely try to use SL tires for good ride quality if going to use 17’s.