I spent the vast majority of my time soloing. Just my nature. I liked grinding out the things that I wanted to do.
When it came to TFs, trials, and when I was feeling a tad more sociable, my first call out was always to my SG. After that, to a channel of our allied SGs, and after that, I'd throw it out to the more public channels. I'd generally end up with about half friends and SG mates, and about half PUG players.
I always enjoyed the PUGs, mostly because my one rule of teaming is: take anyone who wants to come, any toon type, any archetypes, any powersets (except Demon Summoners, because f*ck them). I never ever tried to construct "ideal" teams. Bring what you want, and we'll make it work. People were often grateful to get the chance to use some of their less popular characters, and it led to making some great in-game friends.