In my opinion,
- D6
- D10
- The Nail
- Book of Belial
- Candle
- Guppy's Head
- Tammy's Head (sometimes)
- Blank Card (often)
Probably a couple of others. Krampus was marginal before. Now it's just a non-starter to me.
I don't see how most of those could compare to the head.
-The dice. That's a given.
-Nail. No. Slight damage up, break rocks, and a heart. Big deal. It's a devil deal usually too so there's that.
-Belial. Yes. I'll go with this since it has a 100% chance to spawn devil deals now I believe.
-Candle. They're even at best. Krampus head can clear a very troublesoom room within seconds, candle you still have to work at it.
-Guppy's head. Not even close. A few flies you can't control that even sometimes end up getting you hurt.
-Tammy's head. No. This item is only good in rare synergies.
-Blank Card. No. Again only good in synergies. You can lug this thing around the whole game and not see a good card to use it on.
Krampus's head was just too good for several reason:
1. Low charge count. So you don't have to really save it for worst case scenarios.
2. Huge damage. It can single handedly oblierate rooms and bosses.
3. 0 cost devil deal.
4. No drawbacks at all. There's no required synergy, there's never a time you can't use it, or any negative aspects at it at all.