Remo 3mil Ambassador Snare. I tried the Evans equivalent once and it was just fine. Tuned up easier, too!
I have a few 8x14 snares that I love; one Gretsch Swamp Dawg and two DW Collectors BNOB, and I've recently experimented with using the 2mil Diplomat on those to get more crisp snare response. So far so good.
With all due respect to Cody at Sounds Like A Drum. I like to semi-crank the bottom head to G (392 hz-TuneBot).
The bottom head is like a treble control. I miss the high end response of the wires at lower tensions.
I am good with a 3mil head from most of the major manufacturers. Currently I have 21 snare with Aquarian, Remo and Evans all represented as snare side heads. I've tried 2mil before and got a good sound with great sensitivity but that sound didn't last as long once the bottom head began to stretch. I noticed that the 2mil head stretched much easier. I use a very tight tuning on my snare heads and the 3mil works better for me and has more meat to the tone in my opinion.
I've used 2-mil, 3-mil, and 5-mil. I've used hazy, clear, and opaque films, and smooth and textured films. Remo, Evans, Aquarian, Ludwig, and Attack. I think it would probably be faster to say what I haven't tried than what I have, actually.
After all of that, I've settled on the Remo clear Ambassador no collar head. For me the mechanical benefits of having a no collar head outweigh all of the sonic shading other films and thicknesses offer.