We found SportPort made launching and landing the boat easy for both the 3,000-pound Tahoe Q7i and the lighter Sea-Doo Challenger. There was a steep step up and step down when loading and unloading the boats, but once we found the right speed of about 1,500 to 1,700 rpm, the Tahoe settled nicely onto the dock and stayed there. PWC landings were a snap, and all craft were held high out of the water for dry storage.
VersaDock was also an easy-loading dock at similar speeds. The step up wasn't as steep as other docks, though, thanks to patented V-entry half-cubes with a notch which made lining the boat up on the dock easy; it also reduced the step up to the surface. The Tahoe was a snap to load and unload, and this dock can be configured to accept much heavier boats.
CanDock has a steeper step to load and unload, but the buoyancy makes it an ideal dock for large boats. The step up requires a pretty hot throttle of between 1,700 and 2,000 rpm.
ShoreMaster only makes drive-on watercraft ports, and they worked fine. A roller at the entry point made the step up easy, and once in place, the Sea-Doo stayed put.
EZ Dock also used rollers on boat and PWC ports. The trick is to nudge the boat gently against the roller and then accelerate to 1,500 to 1,700 rpm (or maybe a little more) and hold it there while the boat walks up the roller. Hit the entry point too hard and you'll be replacing a roller.
There are common threads among all drive-ons. First, you need to ease the bow against the entry point with a minium bump. Second, it's better to undershoot the landing than overshoot it. After a few landings, hitting the target every time was easy. We could shove most boats off either by jogging aft in the boat and stopping suddenly, or by leaning against the bow and nudging stiffly. All drive-ons come with a winch that applies the reverse force to back it out for smaller drivers.
We liked the way the rollers worked on the ShoreMaster and EZ Dock, but if heavy boats hold them in the water in a salt environment, fouling could disrupt the action of the roller and barnacles could scrape the boat. SportPort, VersaDock and CanDock are top choices for saltwater use.