I started with some really old sites during the time when there were the shonen big three running, think more than a decade ago
Archaic sites that didn't have a login function and likely don't exist anymore.
Then I also used Mangafox as a side thing, as there were some manga that weren't on the first side and it was easier actually having a library now for tracking.
Tried some others and eventually made Kissmanga my main provider, probs a year or two before the
incidincy, where I migrated on the day when it happened, after having had to work to bypass the anti-adblockers that shitsite tried