I think I found 4chan via a post on YTMND about the Habbo raids by /b/, although /b/ didn't really keep my attention as much as /a/ or /jp/ did.
I lurked until I heard about 8chan during that whole shitstorm period, and liked the concept. From 8's /tech/ I found my way over to Lainchan, from there I saw Sushichan.
Part of me feels like /a/'s quality has gone down overall, but that just might be my problem - imageboard culture tends to be ephemeral, at the best of times.
Sometimes it feels like I'm watching the rise and fall of an empire, except instead of watching a city born of brick, made into marble and reduced to ashes, it's just a pit full of shit being filled with more shit.
I haven't posted in a while, but I lurk occasionally. 8/a/ is closer to my pace, anyways. Just enough posts to keep things feeling like they're moving, with the occasional thread that outlives some smaller boards.
I don't go to /jp/ spinoffs as much.