I highly recommend the weber performer with the gas ignition. It does everything, and with the wsm, you would be in serious business. If not that, I woud get the 22.5 or 18.5 inch ots (if you have it on a wooden deck, might wanna get the gold model.
You can probably get either of them on Craigslist, and if you don't see the one you want, just wait a little while.
Weber One Touch Gold
2001 Weber Genesis that is no longer used since the OTG