Grime is the best music from this period, so I can understand picking the most influential or the best grime artists. My only qualm with that would be that grime had a short creative lifespan and didn't really evolve beyond the mid-2000's.
In terms of influence T Pain popularised autotune. The novel use of autotune has lead to some of the most paradigm shifty music of the last 17 years; late-00's dancehall, afrobeats, chicago bop and the post-Future wave of Atlanta rap. But while T Pain's been influential I don't think his music can be said to be the best.
I'd personally pick Kartel. He's made lots of music, it's diverse (novelty songs, daseca war tunes, melodramatic ballads, alien autotune tracks, virtuoso word bombardment), he's got tons of choons under his belt and has done some of the most interesting things with autotune.
I'll put Young thug in 2nd place for similar reasons; diversity, choons, paradigm shift, lots of music.