Board Thread:General Discussion/@comment-25926288-20170429134340/@comment-25926288-20170804015817

Doing something else, but (statement from Elizabeth Mitchell, which does have a corresponding script-related thing, so I count reasonably legit),

"Emma appears to be stronger than the Snow Queen. Is this something the Snow Queen should be worried about? Worried about Emma’s powers? Well, sure, Emma is very powerful. But I think, at this point in time, we’re dealing with a pretty powerful lady in the Snow Queen. She might have a little more up her sleeve than we think. However, I think Emma’s raw power is possibly stronger than the Snow Queen’s—possibly, we’ll see. She’s had a lot longer to figure it out."

link: http://ew.com/article/2014/10/13/once-upon-time-elizabeth-mitchell-snow-queen-spoilers/

In 4x03, Ingrid also questions Emma with "Do you think your powers are a match for mine?"

So, I guess we probably could argue that Emma's raw power is on par/greater than Ingrid's (just less experienced).

It's hard to place many others, but I guess for raw power: Emma (and Zelena's really hard to place)

Ingrid

Gideon

Regina (Gideon practically owned Regina time and time again, but I think that's mostly because Regina's a slow caster, although he was able to create a portal with little assistance.)

Cora (often seemed Regina's equal though)

Elsa (could be argued to be up there with Ingrid but nothing says so)