I have an older Arachnid. Kids can get it to stick if they stand on a chair. I was super concerned about injuries and damages from darts, but ao far, so good. I have it right in the way of a major thoroughfare too. They don't get free range to play it on their own though.
Looking at the game lists in manuals I haven't seen a huge difference between Galaxy (top gun) and galaxy 2. But I'm not a dart player, but for casuals the Galaxy has fun games.
Parts for Galaxy seem to be harder to come by, don't know about Galaxy 2 parts.
IMO Arachnids are better than the Valley Cougar ones because of the monitor and the game variety is much more approachable for average people it seems.
Also, people say that they'd like seating or at least more space to stand when playing darts at my house... Sigh. Where do they think I'm gonna get space for a chair?! That's potential floor space for a game!! =p
*Picks up phone, looks up phone number for a general contractor*
"Hi, do you do home renovations? Yeah, I'd like to expand my house. Uh-huh. No, not adding a game room or a garage. I'd like to increase the square footage for a chair...."
Seriously though, seating is important, just not nearly as fun! ...Although it's probably easier to fix a chair than an arcade game... Hmmm... maybe I should join KLOCC (Killer List of Couches and Chairs)...