jointhefediverse.net seems to be a commonly linked resource for directing people to join the Fediverse.
Curiously, it does not list Lemmy under the list of Reddit alternatives. Their GitHub README explains why.
Previous relevant discussion: https://lemmy.ml/post/78808
I ran a kbin instance, which kbin forked, and man it was so resource heavy compared to lemmy. Quite expensive to run at scale. Has mbin fork helped with that?