I agree. Take the nonstop back from PRG (I've only ever seen 763s, minus 332s a few summers back...not 764, not that it really matters, but I mention in case it matters to you). Plus in Y I find the 767's 2x3x2 seating preferable to the 747's 3x4x3.

Also the ease of transiting at AMS is another positive (though I can't speak to FRA).