LaBrie, but Allen comes in a very close second place. Gildenlow doesn't kill me; he's good, but I find Allen more passionate in heavy songs and LaBrie faaaar more passionate. Allen is really good but lacks of passion in soft songs, while JLB is dedicated both in heavy and soft songs. Just wish LaBrie was as stable in live performances as Allen, and this is why Allen comes in a close second place.
Additionally, Allen's Beard Kicks ass.