Chuck, I myself use two home made easels.
18mm MDF with moulding on two sides, 12x16" & 8x10" with all paper sizes outlined in a black pen.
Very accurate and fast if using RC paper as RC paper mainly sits very flat. Sometimes (rarely) I have a bend I have to reverse bend out.
The very best easel I've used was a home made vacuum one which held paper absolutely flat.
My experience in commercial darkrooms, is that for 12x16" and above sizes, four bladed easels make border accuracy very easy, once set up, if you wish to make borders that is.
Currently in my own city, there are some rather cheap brand new four bladed 12x16" easels I'm thinking of.
One consideration is your baseboard size. Once you get a largish easel, your enlarger baseboard can be a limiting factor, especially if you do a vertical print that is a section of a negative.
Mick.