I have a '04 Hustler FasTrak 42" w/Honda GXV530 engine. It pre-dates the Sport that you're looking at. It has 220hrs on it (I can't believe the hourmeter to be accurate). Warranty has taken care of one deck spindle (I hit a property stake) and the drive belt (it simply came apart at the seam). I've had to replace one idler pulley on my own (my frequent washing probably contributed to the bearing failure). I have zero complaints and wouldn't buy anything but a Hustler. They were the first zero turn mower (1964?). They've been at it a long time. I've used mine in, both, residential and municipal settings and am trying for an annual contract. If I get it, I'll be upgrading to an X-One or Super-Z w/60" deck.
The smaller, 18" tires of the Sport have a tendency to spin easier versus the larger mowers, because of less traction. The narrower track of the drive tires exerts less leverage on the length of the mower, which means it'll spin the tires easier than the larger mowers, when turning. It's nothing major. But, if you plan to sidehill the mower, you'll want a wider chassis with larger diameter tires. The smaller diameter tires ride rougher, too. I run mine at 7psi and have a lot of Slime in them.
When I bought mine, I primarily compared to eXmark. The biggest difference was that the Hustler was more finished and, at that time, the eXmark was built on a much larger chassis with the smallest deck being a 54". The Hustler dealer is blocks away and the eXmark dealer is 50min away. At that time, eXmark built Toro's chassis and Toro made their own deck, which was stamped. Never buy a stamped deck as the material is much thinner at every contour and will bend/fatigue much easier. The above mentioned Bobcat has a bolt together chassis. Never buy a bolted chassis, as it doesn't have near the strength of a welded chassis.
The eXmark Quest looks to be closer to the Hustler Raptor, based on engines versus deck size.
If I were looking at all three mowers, I'd go with the Sport and 54" deck. The 54" deck will give you 6" of trim width on the left side. That's a huge deal. I wouldn't want all the plastic body crap of the Raptor or Quest.
If you search the lawncare forums, you'll see that Hustler gets the highest marks for quality of cut. My neighbors can vouch for that as my lawn never has windrows of cut grass, no matter how tall it is when I mow it. The municipal property I mow is routinely 1' high and my mower goes right through it, at 5-1/2" deck height. I keep an extra set of belts and blades, just in case something happens over a weekend or when I'm in the middle of nowhere mowing.
Lastly, I wouldn't consider any other brands than what you're looking at. I think you'll be happy with either mower. Dealer satisfaction should be just as big of factor as the mowers.