Larger wheel gives better leverage/easier steering (probably not an issue for you since you won't be running super-wide tires or added caster) but does reduce your knee clearance, which could make ingress/egress more difficult. The smaller wheel will also open up your seat options a little, I'm thinking all things considered you'd like it better.
I have a large wheel on my Bug, and with seats from a Lexus it was a little hard to get in & out - back when I had bad shoulders, knees & hips; my son fitted a quick-release hub so I could pop it off when needed. After getting both shoulders, both knees and a hip replaced I haven't needed to use that feature anymore
Your GM column has a tilt feature, doesn't it? That should be nearly as effective, so you should probably just base the decision on upper-body strength vs knee clearance when the seat's at the desired position.