First of all, I'll say it before someone else....do a search on trailer tires and you can spend hours reading on the subject.
I'd go with Maxxis....just put a set on my Minnie as I just didn't trust the tires that were on it even though they've been fine for a year.
Marathons seem to have improved, but the Maxxis get more consistent positive reviews. I did a little reading on the Greenball tires, but decided to go with what I have had good results with before.