[Subaqua]

yup, alpine butterfly is what I would suggest too if you want a loop in the middle. here is what I think is an even easier way to tie it, if it can get any easier.. and simple to teach someone else. Method 2 : Single-Loop Knots

 

[Subaqua]

A butterfly knot is more easily made than in the two examples given, simply twist the head of a bight twice and pass it through the resulting opening. Where you place the twist determines the size of the eye.
By the way, doing the same with two bitter ends instead of a bight produces a carrick bend.

Method #1 for an example (in the link from my previous post): Single-Loop Knots