Both were bad, but not the same level of bad. Sheith had some shitty fans who ruined the whole fanbase if you want to view it that way, but Klance had ALL shitty fans. There was no decent fanbase to ruin. I am not even exaggerating when I say I only encountered two Klance fans EVER who were decent. Sheith was about 30/70 on the batshit/decent ratio. Sheith's batshit tended to be elitism and entitlement to their ship being canon, while Klance's was that plus doxxing, death threats, sending CSEM to Sheith shippers. This is not a both sides issue, and if it looked like that to you, it's because you only rubbernecked at the fandom without being in the middle of it.