I bought a hydraulic one off eBay. Don't like it, too much play in the (generic) seating that allows a little movement. And that can be catastrophic if it lets go and you haven't got the restraining chain on properly.
Don't be tempted to "protect" the paint on the springs when using clamp types either, and try to tighten evenly and also undo evenly. I had one slip round the spring which ended in a little blood being spilt once... As with any stored energy exercise extreme caution!