I think with CoV being relatively new your going to get alot of fly by night SG's which are there one day gone the next or inviting every tom,dick or harry into the SG just for prestige.
My advice is do what your doing and play in alot of PUG's and get to know people and SG's untill you find one that suits you.
Theres alot of well established SG's from CoH who are quite large but i tend to find you just get lost in the mix so i tend to perfer the smaller/medium sized SG's where you feel like your actualy contributing instead of being just another prestige drone.
But like i say its all personal taste 
Defiant's GoEH/MILITIS METUS
i dont think it matters tbh i have hardly ever got sg teams and had to rely on pugs throught 2 toons to 50 
, amd were talking reasonable sized sg as well
My experiences with SG's have been similarly disappointing for all the same reasons (oh, and you can add low-lev SG members totally unknown to me begging for influence to my list of gripes) Anyway, after having tried loads, all a waste of time, I doubt if I'd even consider accepting an invite to an SG again.
Unlike you I've also found PUG's to be pretty much a waste of time too. The only groups I'm aware of personally that seem to funtion well and have any real continuity tend to have at least a core of people who actually know each other in Real Life. As I don't happen to know anyone else who plays the game I tend to just play solo now.
I tend to use my Global Friends list first when looking for teams, but then theres a fair amount of crossover between that and the SG. Of course the other thing is coalitions, some great groups in the coalitions with the SGs I'm in and its a wide net to find teams from. I like keeping my eye out for people asking for help with AVs on those channels and normally start my team with either people from Global, SG or both. That said most of my Global Friends came from PUGs, the first SG I joined was from a PUG, the SGs I'm in now are with people I met through my first SG............ PUGs can lead to good things, you have to start somewhere.
I think since Global came in people should be using it more. If I was new I'd rather build up my Global friends first, then if I noted a few of them were in the same SG, then I'd see if I could get into that one. Chances are you'd get on well in their SG cause you know a few of them already and you'd be introduced as a friend. I dont think trying to get into an SG cause you've herd good things about them is a great idea, they have to be people you know you want to spend time with, not people you've heard are cool.
That just my long winded advice............. and of course I'm happy with the SGs I'm in, they're the best on the server, obviously 
(anyone who doesn't think their SG is the best to be in, is in the wrong one)
"Well, they found my diary today.
They were appropriately appalled
at the discovery of the eight victims
They're now putting it all together.
Women wrapped in silk
with one leg missing
Eight legs, one body, silk,
spider, brilliant!"
Hi all,
Ive been playing CoV for a few months now (first online MMPORG - no CoH) and have had some interesting experiences with SG's
I've been a member of 3 now - the first 2 basically used me as a prestige [censored] and offered nothing other than the teleporters - never teamed up after intial mish never really helped much at all. The third were a real freindly bunch played together quite a bit but none of them have been online for weeks. Ive found my education of the game and freinds list have been massively boosted by PUG's.
All I'm wondering is - have I been unlucky or is the best thing SG's have to offer is the shortcut Teleporter system between zones? - If I have been unlucky can anyone reccomend an SG that is kind to newish players?
cheers y'all