I've never heard of powerline, but I've never had good luck with wireless. Even in the office, where I'm sitting across the room from the router with nothing blocking it, my internet cuts every half hour or so. The router needs to be reset twice a day almost every single day. I'm looking forward to finally getting the hardwire lines installed before I get back to the office in the summer, because this wireless business is annoying the hell out of all of us here.
At home it's not better - even my father whos computer is connected directly to the wireless router via ethernet has problems and the router at home needs to be reset nearly every day. It's at the point where while I'm at school he disconnects the router entirely and just runs straight from the modem. (With absolutely no issues, I might add)
It's not a lemon router, either, as we've had 3 of them and each and every one has had the same problem.