>>My least favorite in terms of looks are the R44 and R46, mostly for the huge, monotonous grey breadbox exterior, but also for the the cramped seating arangement (very uncomfortable to sit forward or backwards if you have long legs),<<
And the R-40s are better? Their seats are really bad, with short backs that are quite strange to sit on.
And I think that the R-44/46 are the BEST looking cars. They're curved in the front (storm door, etc.). And they just generally look more 'professional' than the R40 series (which looks sort of like they're, well, rumpled). The R-44/46 interior colors are the best of any subway car.
But as far as performance, both groups of cars mentioned are lacking.