i dunno, I haven't played brawl in a long time. Is he new to the scene?
Top Deck is more casual than GW I think. GW is the "main" weekly, and has a better venue than Top Deck...but Top Deck is where all the cool people go lol. The turnout isn't very big...around 30, but I hear GW isn't that big either, ever since the move from PnT to GW the monday weeklies have suffered due to GW's location and Vegas scene being relatively young and not having cars to get to that side of town.
What part of Vegas/Henderson are you? If you're close, it wouldn't hurt to check out. I'm there almost every week as my bros tend to go there often.
Also, they have melee and blazblue, something GW doesn't have