Babylon 5. Now that's old school if you're weaned on NuBSG but it's great. Story arcs, character development, SURPRISING developments (something Trek sucked at), politics, huge cast, grey area ethics, humor.. frankly if there was a fandom as active as Trek and a forum as active as this one devoted to Bab5 I probably wouldn't be here.
That said I did love NuBSG. I watched it recently in 5 weeks and I was quite obsessed with it, to the point of dreaming about it.