Hydraulic powered are generally the top tier in both price and performance. Watermark is the local dealer for the Sunstream lifts. Ours is about 12 years old and have had zero issues with it. Can’t beat the convenience of a remote.
Technically you are required to get a permit from DES. See the DES website for details (
https://www.des.nh.gov/water/wetland...areas#faq34821) Watermark handled the permit for us when we bought. But I got the sense that many do not obtain permits.
Lifts will need to be removed for winter in most cases, for both freezing expansion of the frame and ice flows. That is the main downside. The main exception I’m aware of is if you run a dock bubbler and are in an area where you wouldn’t worry about ice flows in spring you can probably get away with not pulling, but risky if the bubbler fails. Also, technically NH law requires it to be pulled for winter as it is permitted as a seasonal device. There are some creative ways to do this - a post on this forum a few years ago with a picture used 4x4s cantilevered over the dock chained to the top of the lift so the lift pulled itself up and was suspended over the water. Was pretty ingenious. But doesn’t work for all dock set ups.
We pull ours ourselves, but it is a project as I’m too cheap to pay around $500/year for a service to pull and drop.