Linksys are usually good stuff. My BT one doesn't have an antenna either and I've been happy enough with it. I have had absolutely no problems with BT regarding reliability and never suffer from any buffering when streaming even in HD, but they are just getting so damned expensive. I am wary of going elsewhere though and many locals seem to use Sky or Talktalk and constantly seem to be mentioning it going down or having problems with it. Not sure why it should mind you as it all just comes over the same wiring.
My contract is up in December and even with BT's not very generous fiver off if I renew, it will be £65! Sky, etc are around £26. Huge saving and, yes I know they will also shoot up once the contract is up too but at least it would give me a couple of years savings.