I love sweepers too. They're swingy but their mere existence adds a lot of excitement - for the players and even spectators. But as I am running a lower powered cube that's not super fast, I have to be very careful in how I balance them. I run these currently:
White is king of boardwipes and gets 5 mana hard sweepers that can have small upsides. However, there are only three and one requires at least a few blue sources.
I love the bounce sweepers blue gets, and Aetherize is such a great card to have in a format. Players quickly learn to fear it.
Black gets four boardwipes, as it's king in killing, but it sweeps more conditionally. It's always size-based and sometimes scales with a thing you do (Mutilate) or takes time (Necroplasm).
Red gets two pretty strong, scaleable sweepers. But Wildfire/Force are clearly more specific buildarounds that can't be thrown into every control deck, and Ryusei is at it's best if you have ways to sacrifice and recur him at will.
So, these are 14 cards at 680 total, and with some quite conditional ones. That's my way to keep sweepers as a strong and interesting tool for control decks, yet also keep them in check.
Edit: people might say I just love talking about my cube and they're right, but I also thought it would be cool to have some examples from a cube much lower powered than most mentioned here so far.