I have 2 x100's 1 main 1 alt. my main got extremely lucky with follower procs. my alt got it so bad that i dont even bother with it when it comes to missions.
Best so far was a tavern recruit. Got Matoclaw (cow from mt. hyjal in cata), who was blue to start with, had epic mount AND is scavenger. Other than that, pretty average followers.
My best was Soulbinder Tuulani (on my alt unfortunately). She came with group damage (default) plus dispel, with the traits Epic mount, burst of power and bonus chance with Tauren. The epic mount + burst of power is crazy good synergy and I so badly wish I could move her to my main where I really need it for mythic highmaul missions. She goes great with my Olin Umberhide who also has burst of power + Tauren.
My Greatmother Geyah with epic mount + stamina makes me sad though, only works well for Abrogator missions.