I shoot to try and use the whole neg.
I crop to get the best out of the neg. I don't crop to the paper size.
Most of my work is done on 10x8 inch.
Just started using 12x16 and it's amazing, though you need a reasonable neg. Oh and I only shoot 35mm. Would love to shoot medium format but I don't know that it will ever happen.
Possibly going to try some 11x14 soon, picked up a brand new 11x14 lpl easel for 20 quid the other week. 11x14 could be a handy size for those negs that I want to print big but need a big crop.
Had never heard of 11x14 till I started looking net forums.
Nor do I know anybody in Scotland that stocks it, though silverprint in London have it I belive.
Meanwhile my weekend print session was ruined late last night by a kidney stone attack. Had to throw the fiber prints out of the bath so I could get into it to try and kill the pain. Today was completely lost as I'm totally shattered and I'm now as far behind with my current project as ever!