Seattle area, never traveled out of state for one so I go to PAX Prime (technically an Expo I guess but whatever) an Emerald City Comic-Con on the regular and I've gone to Sakura-Con twice and Everfree Northwest once; not a "veteran" like some but I like to think I'm a regular.
PAX: Fun stuff, I would consider that I get the most enjoyment out of this one since it's all games. I usually float around (as is a theme for me at Cons) and try to check out stuff that doesn't have a line too long. That's the thing, packed with people, if you're not the waiting or crowd type, really won't be thing. I'm not really that type either but I tolerate it at worst and make time for at least one thing I know is gonna have a long line, Gears of War 4 this year, Halo 5 before that, but only one.
ECCC: This one I'm gonna say I get the most *personal* enjoyment because I like getting stuff and I love getting my comics signed. I never make time for celebrity guests, too expensive and too long for my tastes but hey, comic writers and artists are free for signatures so heck, I go for it.
Sakura-Con: Big anime con, or so I hear, went once when I was into anime, liked it, didn't love it but it wasn't bad I suppose. Masquerade Ball was fun, got my yearly dose of feelin' like a man, it's a good memory. Went again for a friend when I wasn't really into Asia-brand entertainment, wasn't great but I was with friends so it wasn't bad either. Would've gone to the Ball again but there was a concert that night that I wanted to be at more.
Everfree Northwest: Seattle brony-con. What can I say, used to be a fan. Was always a teeny bit embarrassed to be a fan of My Little Pony so I could've enjoyed it more but I'll say this: The nicest people were at that convention. Back when the ponies thing was in it's heyday, I'll freely admit, we had the worst online presence but I'll tell ya, these attendees, the nicest people.
Oh, wait, I guess there's one more. My hometown tried to get a Con going once, didn't go so well. It wasn't terrible but it wasn't any fun, the books can say they tried and hey, if that's my worst Con experience, I'd say I'm doin' pretty good.
Also a scrub-tier cosplayer here, only ever made one costume, bought everything else. It's fun getting a costume together, probably means more if you make it yourself but I don't know how so, you know. But still, I'm very proud of some of the characters I've been.