I use a bunch of Endoflames (usually 8-16) as starter mana generation, burning charcoal from 2x2 spruce trees, because chopping those down is my favorite way to procrastinate.
My early- to mid-game flowers usually are Gourmaryllis and/or Munchdew to rush towards opening the Alfheim portal, but it depends a bit on what else is available in the pack I play. The Gourmaryllis never really gets a proper automated setup. Last time I just made a two dropper thing with animated torch and hovering hourglass to feed it cooked cod and salmon from automated fishing. The Munchdew tends to get a bit more love, being integrated into an actual fully automated tree farm, like a Create-based Quark blossom tree farm, or multiple 1x1 spruce tree farming contraptions. (Although I also already just placed one in the middle of 4 2x2 spruce planting spots – see my comment about procrastination above.)
Late-game I tend to gravitate towards Entropinnyum (if playerless gunpowder automation is viable and fast) and Shulk Me Not. I tried Spectrolus before, but had some trouble scaling up wool production. Back in 1.12 I also built my base around a slime chunk and created a megatorch "perimeter" to optimize spawns, but the mobcap mot being player-specific unfortunately made spawn rates pretty meh when anyone else was on the server. (This would work a lot better today, especially in skyblock.) I'd definitely like to try automating a Rafflowsia at some point, too.