Going to preface by saying I still use Reddit occasionally alongside Lemmy AND Tildes sometimes as well. I just like talking to people with similar interests.
Most of us came over to Lemmy (in my case, originally kbin) because of the 3rd party app shutdown and API apocalypse. I still use Reddit since it has a lot more communities I'm interested in so I wouldn't be an ex-redditor per say. I'm not nearly as active as I used to before 3rd party apps got shut down.
I was always indifferent towards Reddit as a platform since I mostly just felt connected to the communities there. I only use more niche subreddits related to my interests and was never active on any with over 400k besides from askreddit, so I avoided most of the stereotypical bad things about Reddit's community and the whole "Reddit is becoming like Facebook" stuff. If Lemmy gained these communities I love, I'd stop using Reddit completely.
The community and content matters to me a lot more with link aggregator type platforms, the software less so than it does with microblogging platforms like Twitter and such. Spez sucks for what he did but I really don't care enough to criticize the dude one year after the Reddit migration and the failure of the blackout. I like Reddit's sheer amount of content available and don't care for the software/anything paid on there, and I like the technology behind Lemmy but the community offerings less so.