When I was there in October - alone; something came up and SWMBO had to cancel at last minute - I drove around and checked out all the shops. When I walked into each I said I was just checking out the shops in town and theirs was the first I was visiting. A few impressions:
Scuba Views - Staffed by a couple of Jr Dickheads; stated, "We're the only REAL diveshop in town." Tried the hard sell on their upcoming Mexico vacation. PADI shop.
Gr8 Divn - Good folks, chatted for a while with them. I'd recommend this shop - check out the Wall-O'-Vintage-Equipment in the training room! SSI shop
Dive Into Fun in Henderson - Another good shop. Smaller shop with a decent selection of gear. I probably spent a good hour there yakking. I'd recommend this shop. PADI shop.
AAI Neptune Divers - They weren't open the two times I got out there. NAUI shop.
Sport Chalet - Chain of sporting good stores, not a LDS. Didn't visit.
Lake Mead Technical Divers - No address listing, didn't visit.