Not the best or the most flexible ones, just the ones I enjoyed the most. Usually ones with weird interactions or ones that do something special in that specific deck. Basically just stuff I tried out.
I played the monoblue Brain in a Jar deck for a while. The idea was to sift through the deck casting random instants and sorceries until you hit critical mass in your graveyard and then cast Rise from the Tides. Alternative way to win was to chain Part the Waterveils. It was definitely an interesting deck. I just felt I needed to have another avenue to victory after sideboarding, so I brought in these beauties. Opponents would, of course, cut most removal from their decks, so it was pretty invulnerable. It was also a way to dodge discard. Because Transgress the Mind was the prevalent discard spell in Standard at the time, I would use something like Nagging Thoughts to put the targets into the graveyard before giving them legs.
So, I was playing this horrible monored tokens deck in Standard. It’s one of those “please don’t try this at home” things. It was running stuff like Molten Birth, Goblin Rally and Ogre Battledriver in it to combo out and kill the opponent. Every once in a while the opponent would stumble and I would just rush them, but sadly, the deck didn’t do much against the prevalent deck of the time: Sphinx’s Revelation based control decks. So, what to do? Possibility Storm was the answer. Not a good one, because it costs five and can still be Detention Sphered, but on the other hand, they basically couldn’t cast Revelation or counter anything while that thing was on the table.
Four mana 4/4 with flying and haste sounds pretty good. There is a drawback though. Then again, if the removal opponents are running is sorcery speed… What else am I going to do with all that mana in a monored aggro anyhow?
The greatest thing about this is that I managed to talk other people into playing it as well. We were playing a Bant tokens deck when Collected Company was the biggest thing in Standard. Profaner would just decimate that deck. Gideon, Ally of Zendikar was the one who usually had to take a hit for the team, but I guess that’s sort of his job.
This is my hipster inclusion in the sense “I was Ranger’s Guiling long before Blossoming Defense”. Now everyone seems to be playing Defense in my LGS, but back in the day catching my opponents off-guard with it was always fun, because no-one expected it. I would generally run maybe one or two only, because they would definitely catch on.