I'm not a professional, but I've had Trane systems in several of my homes, and they have been very reliable and trouble-free. Recently, in our new home (well, new to us, but still 30 years old), we replaced the first floor HVAC system. One vendor tried to talk us out of Trane noting that "since they never break down, you'll end up keeping it forever, and it will eventually be very inefficient, but since it never breaks down, you won't replace it, and you'll suffer from the inefficiency." That's what he said...I swear!
We ended up going with a Trane system. 90% efficiency gas furnace and 16.75 SEER AC system. I understand that Trane and American Standard are part of the same company, so you might look at either one.
As for SEER rating, I live in Atlanta, so I want a more efficient unit because I'll use it more often than someone in the north of Ohio (I'm from Cincinnati, by the way!). We've got a 16.75 SEER unit, and I know the minimum you can get is 13 SEER. That 13 SEER might do you just fine based on your limited usage.
Hopefully, a good vendor could do an analysis of your cooling needs and let you know how much you'd save on your power bills with a higher SEER system so you could see the payback.
Good luck, and hopefully one of the very knowledgeable professionals in this forum will respond as well.