I always like to have HOB and a cannister on the same tank. I have an XP3 and find it very easy to work with, I service it once a month. I would setup a couple of AC110's and an XP4 if you are going with a fully stocked tank. You could do one AC110 and on XP4 as well. I like using the two different types mainly for bio filtration. I keep them on a staggered service schedule to not shock the tank. I don't know if this is best, it is just what works for me.
Good luck, setting up a 125 will be a great experience. Post pics if you get a chance.
Good luck, setting up a 125 will be a great experience. Post pics if you get a chance.