Red-Eyed Vireo

I said I agreed with red-eyes and not the warbling

Not a warbling vireo, no black stripe above eye on warbling.

Red-eyed vireo

I agree as the Warbling Vireo would be paler

Wow. A real challenge... at least for me. :) I'm going to throw out a guess... Red-eyed Vireo. According to the Sibley's guide, p. 342, "grey crown, with distinct dark border... long flat crown accentuated by eye-line". Yours looks like it's got the feathers raised on the head, so I'm bypassing the "long flat crown" bit.

Anyway, I'm calling it a Red Eyed Vireo.