I don't know if it's the best, but I learned on Sig Kadet Senior (arf w/ ailerons) and OS .46 FX. Plane was incredibly
stable and flew great. My instructor had me taking off landing and doing some basic aerobatics (loops and rolls)
the first day. We waited till the second session to do sustained inverted flight. Hey Dick you forgot to add
PT-40 and Kadet senior to the list of trainers you've flown.

I don't think it's so much the BEST trainer that you need to look for, but a good instructor with patience
and people skills is a must.