Ok, So I did some rereading of Elantris. Here's a few interesting facts.
1. Elantrians can die. They heal very fast, and can survive many wounds due to this, but if you stop their heart they will die (according to Raoden at the end othe book). They were also supernaturally strong and fast.
2. Their spells really don't take any time to cast. In any RPG out there it would be the standard one spell a turn, maybe ever more. At one point Raoden casts two spells at one, writing an Aon with each hand and killing two separate soldiers. Also, this is after he'd only had a few months practice. I still think a real master might do some really impressive stuff.
3. One spell can vaporize a man, they do lots of damage.
4. They can heal other people very fast. Poof you're healed fast.
5. Their biggest limitation is that Aon Dor really only works near Elantris. The farther you get from Elantris, the weaker it gets.
6. They CAN create Force Fields. Even when weakened by being away from Elantris, Raoden was able to create a force field strong enough to stop the swing of a man with supernatural strength completely.
7. There is no evidence that they can fly (although I though maybe it mentioned it somewhere) but they can teleport.
So, all in all . . . dang. I just don't see the other hanging with them. There is a reason they were called Gods, not mages. I think that unless you took them by surprise they are probably going to come out on top of any of Sanderson's other creations. I think their force shields are probably strong enough to stop a blow from the Lord Ruler, and their attacks are more then enough to kill a Kloss in one strike.
This is also based on what we see of them, minutes after regaining their powers. Who knows what items of magic, etc they can create.
As to the Lifeless vs. Kloss debate.
Kloss, hands down. One Kloss is probably worth 10 lifeless.
But, don't forget about Kalad's Phantoms. I doubt Mistborn, Kloss, or Ferchemists could give them much of a challenge, and they also only take one breath to create.
Of course, the Elantrians would still kick their trash . . .