I spent months researching different models from around the world and ended-up buying a FloatLift from Sunstream in the US (www.FloatLift.com
). They are more expensive than other models but they're the best I've seen.
You drive your boat between the floats onto rubber skids; press a button on your keychain and the hydraulic rams pull the floats downwards and inwards to lift you and your boat in c30 seconds! Brilliant! The floats are foam-filled so are unsinkable and your boat stays perfectly level throughout the lift or launch!
I have had it since 2003 and haven't had a single issue with it.
Let me know if you want more information or advice on it.