I've been using Teebo as my leader. I was using all three but dropped Elder and Scout since they're not really farmable and everyone else I have have outpaced them. I'm still hitting those few nodes to try and collect the rest but that's a long term project (I really wish they were more accessible; Elder was actually pretty nuts until he was out-leveled). So far I'm loving Teebo. He's a ton of fun. He's by far the weakest of the 5 on the team but I'll have him leveled soon enough since he's a GW drop and I'm almost done maxing out Lumi.