I know I've voted for Lords (I-Photo now), but that was when I got DSLR body and other accessories. Don't get me wrong, they are still okay IMHO. Recently, my fav haunt has been TK-Foto, probably it's due to their great range of one-stop-for-all goods. I've bought from SLR before and I think their service is okay too. Orient Photos is okay too. Trust me, not everyone knows everything - even the best salesmen can't know everything unless you're talking to the "active" boss himself or herself (but don't take for guaranted that he/she would know everything either). Each store has its fair share of good and bad salemen/women. But don't forget this "good and bad" can be subjective from person to person. Who is a good saleman to you maybe the opposite for another - it is simply "chemistry" between two parties. If you don't "click" with the sale person, that is just it, move on and see if you can get lucky with the others.
As far as I'm concerned, go into each store with 50 to 70% confidence - to safe guard your feelings towards the store. Not 100%, as you'll only get disappointed if you do so.