I'll plug Plant/Time. Was my main character on Live, capable of so much with what you have. /Time is pretty much all-around buff and debuff set, nearly everything you could want from a Buff powerset, and Plant is a fairly offensive focused Control set (it was originally a Dominator set) with a great cone confusion, strong group controls, and the vines, good god I love the vines. Together you get a ton of solid control and debuff, while also being a strong team support with your excellent AoE heals, Temporal Selection for your whoever needs it and Farsight/Chrono Shift being two amazing team buffs that are just as useful solo. Back on Live I had rolled this specifically to stack Spirit Tree with Temporal Selection for the Hamidon tank; extremely potent +Regen potential between the two, especially with enough recharge to dump 3 trees at once, though I think the current Hamidon strats don't really need this kind of help anymore.
Currently attempting an Electric/Storm. Just getting started with it but I think once I get the Force Feedbacks and KB>KDs in there will be some shenanigans. The combination of abilities makes this combo look like it prefers to stay with the melees, that way your Conductive Aura, Steamy Mist, and possibly Hurricane (if the Repel isn't an issue) all help out and take effect. Endurance Drain and Knockdowns are looking like they're going to be super strong here.