It's also dependent on the person and added creativity. We've all seen people who've built their character to Madara level powers and are still sub-par in their prowess (no names mentioned)
And then you have people who still have Madara level powers and are actually good at it; Bocci-boi.
So we could all take a tally and vote for one or the other, but at the end it's still subjective to the person. In my case I like Rinnegan more. I think Goosh put it in a good way at it's most basic. One gives you more techniques while the other boosts your current ones. They're equally good to me.
Back to the topic...
1) Iburi is counted as a KG. At least in canon Naruto terms. On SL I assume it's the same.
2) Deidara's bakuton in clay form or the kind that just explodes from your body? The latter is the badass one.
3) 8 gates on SL is a KG. It just helps to keep people from claiming it on top of kaguya and so on. Same reason why sage mode is counted as a KG even though it's not.
4) Sage mode I already shared my opinion on it. It's useful and can be OP with the right controller.
5) EMS transforms into Rinnegan. Both are counted as separate as said just to keep a slight power balance.
I'd do this;
EMS, Rinnegan, Bakuton, Iburi. Seems the best for the things you've said you want to keep/can't part with.