WHAT I WOULD DO
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Mine would be MASSIVE. Modded worlds (Crazycraft, Pixelmon, custom modpacks, etc.), Bukkit servers (Walls, Creative, Factions, Survival, Bridges, DrawMyThing, Skyblock, Skywars, Prison, Hide&Seek, UHC, custom minigames that I really don't want people to steal because they're actually pretty cool, Parkour, Hunger Games, Super Craft Bros., etc.), one or two whitelist-only servers because I kind of have business that I need multiplayer test worlds for and right now I'm having issues with that , plain old vanilla servers (as in no plugins whatsoever, which may be a bad idea but I think I can make it work if I haven't already...), and I think I've covered just about everything.
Why? My computer can't handle 1.8 and all the good servers are for 1.8. I'd pretty much recreate my favorite minigames from 1.8 into 1.7. I need modded servers for myself to reduce lag. Vanilla servers... Well, why not? It could be the best thing ever or it could go down in flames (literally... Griefers... xD)