Ummm.... my favorite wincon is which ever one I haven't done yet. I love to win in new and unique ways, particularly when it's a convoluted 4, 5, 6+ card combo. I have a deck built around
Morophon, the Boundless and the bannerettes and warchiefs that also reduce cost for a creature type to make all my changelings free. Then I used something like
Cloudstone Curio or
Tidespout Tyrant to bounce my own changelings for infinite ETB's. I found that if I had a
Gemhide Sliver and a
Gallia of the Endless Dance, I could also get infinite bounces off an
Equilibrium. Then I also have plenty of options on how I'm going to actually turn the ETB's into wins. Though
Impact Tremors is fine, I've enjoyed looking for other cards that make things interesting even once I've comboed off.
That's a combo I designed into my deck, but my Aristocrats deck once surprised me by going infinite in a way I'd never expected. I had
Pitiless Plunderer,
Teysa Karlov, and
Twilight Drover out, for sure, but I don't even remember all the other cards (maybe
Reassembling Skeleton and
Pawn of Ulamog?). Basically I could produce enough mana from sacing the spirit tokens from the Drover to keep reactivating it, but because of Teysa, I got an extra +1/+1 counter each time. I was sacrificing to a
Fallen Angel, and I had one opponent with no blockers and another with no fliers, so I actually won with combat in an aristocrats deck. Only time I've ever seen that happen.
My absolute favorite way to win is completely out of nowhere with a non-threatening deck that doesn't seem to be keeping up. My favorite way to do that is using
Skirk Fire Marshal, a couple untap effects and or damage doublers, and 4 or 9 other goblins, and, of course, a CoP:Red or something that no one worries about until it's too late.