Okay, here’s the scenario. Mankind has been wiped out by a nasty virulent disease contracted from a dirty telephone, leaving nothing but big concrete buildings and billions of rusting cars.
If we give it a couple of billion years, which species is the next one to take over? For the sake of argument all other simians become ex-simians as well, since apelike beings would be too obvious an answer.
My vote goes to the elephant. Mankind had three main things going for it; intelligence, dexterity, and language. Elephants have a long lifespan, are quite intelligent (these two seem to be interconnected) and have their trunks to manipulate all kinds of objects. With a bit of adaption they might even use that thing to evolve a more complicated language.
The problem would be why they would evolve. Mankind had a lot of natural predators that kept the population down and ensured only the fittest survived. (thereby ensuring their own extinction, there’s some nice irony in there.) Elephants, in general, don’t really have that. When animals see a herd of massive, grey, pissed-off mammals stampeding their way, they tend to flee.
Anyway, that’s my short answer, and I’m terribly interested in who you think is the best contestant.