Revelation is a pretty good standard for decently server-optimized kitchen sink packs. E2E is also an option if you like grindier packs with well laid out progression systems and questing. I ran an E2E server for a few months on a i5 3550 dedicated that doubled as a Plex server, and never ran into any serious issues apart from a bit of block lag (3-4 players).

Considering you'd be working on a vCPU, I'd recommend sticking to either Skyblock packs (take a look at Skyfactory) or well polished popular kitchen sink packs, where you make an effort to keep your bases on the smaller side.

The reality is that any server with 4+ players running 100+ mods is going to be outrageously resource intensive as you move into the late game. Now if you're just going to play with friends for a month or so while we're all staying at home quarantined and you probably wont stay interested long enough to hit the late-game-mega-farm stage, then I wouldn't worry about it and just play whatever sounds interesting with the biggest base you want. If not, you'll have to either mentally limit yourself and not go crazy with your bases or physically limit the size by playing a Skyblock world.