We have both at camp that are going to be 8th leaf this spring. B-118 trees have a FEW leaners. MM-111 trees are solid and straight, as are our Antonovka-rooted trees. MM-111 is listed and recommended for heavier, clayish, less well-drained soils.
After the initial plantings on MM-111 and B-118 in the first couple years (2013 and 2014) I went more with Antonovka and P-18 roots to get full-sized, standard trees because of our bear population. The early MM-111 and B-118 trees were to get some earlier fruiting, as opposed to Ant. and P-18 trees which take up to 10 years to fruit. We have a nice mix of MM-111, B-118, Antonovka, and P-18 trees, with some producing fruit and others not quite yet.