What's your preference and why

I like adjustable because not all coyotes are the same size, and I don’t have to fool with belly wedges. Easier to get a coyote off if it gets turned a little too soon.

Ttt

Me to . Adjustable all the way. Everything about them are easy.

Split board for me; no belly wedge needed and easier to remove. But, they should be used properly ie; the proper use of a collapsible/split board requires opening the board to the correct butt width dimension for the pelt size, then putting the pelt on and pulling it down tight and pinning. Pinning the pelt on and then opening the board is incorrect and often leads to improper shape and overstretched fur.

This.
The pelt put up too wide or too narrow for the standards should be discounted; you should think of those forms as being collapsible rather than adjustable.

I have all solid forms because they are easier to lay out and make.

Split boards are no problem re lay out. Just use two1X4 or 1X6 which ever you prefer. Anchor them down, side by side, with the top end together and the butt spread apart to the NAFA specs. Then add the pattern measurements and trim the edges accordingly. No taking inside material off.