I prefer Welch’s Flintstone line.
Spiegelau All Purpose Tumbler L.
Hard to say “favorite” when I’ve only tried one. I’ve got two 6-packs of stemless Lenox “Tuscany Classics” that I bought to pack when flying to a BYO with poor or no wine glasses. They’re a nice shape and a good compromise between the elegance of a thin rim (not that any stemless glass can really be that elegant) and a sturdy enough package to put in my luggage. They were on sale for only $6-7/glass in 6-packs.
I’ve used them all of once.
Thank you for the replies (well, at least for those replies that didn’t include telling me you never use stemless glasses 
). By the way, I just don’t buy the heat transfer thing. I don’t sit and hold my glass between sips, so it’s be minimal at best. That said, I looked up the recommendations so far and like the look of those Schott Zweisels. I’ve had the Riedel Os, but don’t care for the look.
Reidel O glasses, as well.
For outdoors, we use Yeti Ranblers and Brumate Uncork’d Insulated glasses and we exult their virtues every summer. They keep the wine very well temperature controlled!