I'm just glad (so is my wallet) that I started this collection at a time where the figures from a couple of movies prior to AoU are that good, that I don't need to feel compelled to get the entire AoU lineup, just to have the "best"...
I genuinely do prefer the look of Widow and Thor from earlier models... but I think if you are budgeting out one figure per character, then you aren't losing much, if anything... Captain America and Iron Man, AoU has better versions than TWS and IM3... and Hawkeye is a no brainer..
Thor is such a straight swap, that I bet if you took the two figures, posed them separately without their bases, and asked a casual movie goer which was which, they'd have no idea...