I've been playing with a Brain deck for a while now and it's probably my favorite versus deck. It wins a very high percentage of games, but the only drawback is that the games tend to take forever (20 minutes on average, I would say, but I've had games go closer to 40).
Contrary to what other here are suggesting, I recommend not going three colors and staying just U/B. I used to run a Grixis version but the deck is very greedy for double black (Grasp, Languish, Yehenni's Expertise, etc.) and double blue (big Jace, counterspells) and mana issues were a real problem. The U/B version is much more focused on pure control, with only a few wincons. The only reason I would consider trying Grixis again is because of
Dark Intimations. I would even consider splashing red just for that card and will probably try that out in the near future to see how it works.
The main wincon in the deck is
Rise from the Tides. The basic idea is to stall with your plethora of removal, sweepers, and counterspells until you get a Brain on 5 counters, and then cast Rise on the opponent's end step and attack for lethal with a 10+ zombies. If you can't find a Brain (happens pretty often with only 2 in the deck), casting Rise on your turn is also an option, but not an ideal one. The secondary wincon is
Thing in the Ice, but it's not as reliable because, being the only creature in the deck, it tends to eat removal pretty quickly. But this deck flips Thing very easily and if you can protect it and/or the opponent has no answer for it, it gets you free wins occasionally. It also makes for a nice early blocker against aggro.
The key card for fueling the deck is
Pieces of the Puzzle. It lets you find the answers you need while also filling your graveyard for a big Rise finisher.