My thinking with EA games is:
I will get Battlefield 3 on PC, Day 1 for $80. I will probably buy it from an actual physical store locally if I'm paying that price.
I can't wait 2 weeks for a UK import since:
1- I will miss out on all of the instantaneous bitching about every single little issue, perceived imbalance, etc
2- Games like that are great when its new for everyone and people haven't found all the 'spoilts, camping spots, etc.
3- two week gap between BF3 and MW3 and chances are I will enjoy the MP for MW3 more.
I loved BC and BC2's Rush mode far more than conquest and I don't get a sense BF3 will bother much with Rush
Mass Effect 3 will be a console game for me anyway so will probably get on 360 locally.
I don't mind paying $80-100 if the game is good and I get a decent amount of playtime out of it.
I don't see the point of paying the same price on Steam or Origin as it costs to buy in the store. I can pop to the shops and back and have the thing installed in the time it takes to DL.