Grassshopper, Toro, John Deere and Bushhog are four brands I can think of that make offer deck mowers. If I were going to get a front deck I would rate them in the order I listed them, except with Toro and Grasshopper tied for the #1 spot.
I commercially mow and I have a Toro Z-Master mid mount zero-turn. I've used the Bushhog front deck but I didn't care for it too much, though I will say the control arms were in bad need of adjustment which is probably why I didn't like it as much. Toro has been in this business a long time and makes some good commercial stuff.
Grasshoppers have a good name and a good product. I don't know if Grasshopper makes it but I saw a crew of guys clearing a 6"-8" snow off of a parking lot with Grasshopper units with a blade on the front of them. Talk about getting with the program and getting work done!
The front deck mowers are much nicer for getting under stuff such as under pine trees or overhanging bushes. I can't comment on the ride they have too much because most of what I have mowed with them has been a nice graded soft lawn. My mid deck zero turns though have a good ride to them ad when my dad (59 years old) helps me he never complains about being bumped around too much. Regardless of what you get, they offer seats with suspension and I recommend them.
As for mid mount zero turn mowers, Ferris has a suspension on their front wheels, I have never used one but guys who I know that have have said good things about them. There is just something about the Ferris mowers I don't like, I don't know what it is but I just don't care for them. Scag, Exmark, Toro, Bobcat, Cub Cadet/Lesco, Hustler, Ferris, and Grasshopper all make several very well constructed commercial mid mount zero turns. Anything from these manufactureers with a Kawasaki, Honda, Kohler, or even the Cat deisel will be a good mower. Some of their models have a Briggs and Stratton Engine, I'd shy away from those engines and opt for one of the ones listed above.