More intense = Everest
Guardians is all inside in the dark with no visual frights. Everest is outside often, big drops, high up views, intense turns = all very visual. Top speeds are about equal but with Guardians in dark you have no perspective on the speed so I wouldn't compare that.
Guardians isn't scary at all, it's only negative is the nauseous if the screens bother someone. I personally don't find Everest scary but I love coasters. At no point do I feel like I'm not safe, but it is a good coaster.
I guess is what is it that OP or anyone else is concerned about? It is the nauseous effect that some get going backwards or with screens. Or is it the thrill effect that determine the intensity of coasters.
These two are completely different - with the backwards being the only somewhat similar.