I use Old Macs, although I'm not using them atm as my horse is now transitioned and the ground is soft. But I've cleaned them up ready for summer.
My EP recommends Old Macs and I haven't got any complaints. They are easy to fit, stay on and don't generally rub - they come with pastern wraps for when you're wearing them in.
Boas are popular but I hear a lot about broken laces.
I'd have to say the boas. Have old macs which I've used for years, only bought boa boots cos of my 17.2 WB's huge feet
I love the boa's - SOO easy to put on and they feel really secure and tough whereas the old macs were so fabricy and difficult to get on, adjust and tighten - took ages and were such a hassle - however pls note this could be because they're several years old, maybe they have a new design? Anyway I can appreciate the comment about the rubbing with the boas, tho i've never had this problem, have the gaiters and don't need to use them! I think if your boot fits right and you don't over tighten it (common prob) then shouldn't rub. Hope that helps!