i've tried a total of 6 shirts from uniqlo different seasons/years all in the same size which is my regular size extra small slim fit/regular fit. fit was always bad on me. i don't mind paying more for a shirt if i know the cut works better for me. right now the only things i own from unqilo is the ma-1 and heattech items. heattech longjohns and longsleeves are great for staying warm without bulking up on layers too much in the cold.
Feel you brother. It's an unfortunate fate if uniqlo shirting doesn't fit. The fit on the oxford is flawless on me. For most other cotton and flannel shirts I wish they were just a tad roomier. However, a recent EFC shirt fit me much better(although not perfect) than one from 1.5-2 years ago so they're still tweaking.