Currently
At Delta. The training you get is pretty high standard. The planes they use are of course 152's, 172's, Seminole's, Arrow's.
I suggest you take their promo tour for more info.
If you choose this school then I suggest you plan ahead and figure out where you can get the most beneficial lodgings. Delta can and will in all cases provide you with housing if you cannot find any yourself.
I cannot say anything about Oxford since I have no clue about them except that their prices seem to have increased with the years.