Best ATX is [strike]ASUS Sabertooth 990FX R2.0[/strike].
Best MicroATX is ASUS M5A78L-M (about 75$).
The ATX board is better and [strike]just under 150$[/strike].
EDIT: Sorry, I as looking at the price in £. It's about 200$. Sorry about that.
For 150$, the ASUS M5A99X EVO R2.0 990X is the best. It is ATX format, so make sure your case supports ATX, some cases are only MicroATX.