I was planning on using wind just cuz I like picturing tornadoes killing my enemies, but I was wondering if, for a welling mage, a certain element was better. (on HC, btw)

Thanks for any suggestions here!

It depends on what you like. All attack charms can do very well in welling, it just depends if you like consistency or high crits.
I personally like earth for welling, but wind would work as well.

Is ice difficult, because of low max??

nope, b/c ice is very consistent. Ice does just fine

There is no best its all a matter of opinion and preference.

Some people prefer consistent but lower dmg

Some prefer lowww mins but insanely high crits

Some prefer a balance between the two

Some prefer a step below or above one another.

E.g.

Lightning is the Insane high crits
Wind is the step down from that..slightly higher min slightly lower max

Ice Is Consistent
Earth is the step down from that

Fire is the balance

All will well sufficently.

thank you all

To add to what the others have already said:

I like my Ice charms for the Well, because I can tell within the first two or 3 casts whether I am going to be able to beat the monster or not. This is due to the consistency.

The same would hold true for Earth as well, also, Earth charms are a little cheaper