Because the bowl and tank are a single piece, the Ultramax is heavier which makes it a bit more to handle, but a second pair of hands would help with that. The one piece is nicer day in and day out because it is easier to clean. I would opt for the Ultramax, but with any toilet, I use nuts to tighten the flange bolts to the flange. The keeps the bolts upright so it's easier to slide the toilet straight down on to the wax ring. Do not use a wax ring that has a plastic funnel, just a simple, plain ring is best. Either toilet flush is excellent.