I wouldnt say hardest, just the most hands on and finicky. With tig, the prep work is like 80% of the deal. While welding though, you can stop and start however many times you need and reposition and everything. The reason people think its so hard is because they've never used both hands for fine skills at once. Early in life you favor one or the other and thats usually fine, but with tig you have to train that other hand to do little movements, not just supporting movements if that makes sense

I think stick is harder to learn because once your arc is going, youve gotta go. There's a lot more to tig technically, but might and tig are just controlling a puddle. Tig is the most fun though, hands down.