The advantage of a hydraulic plate over a manual plate will be seen the first time you put your engine down in rough water, or very high when idling into a shallow area and want to maintain better control. Tilting your engine to the point that it is almost out of the water, as most of you know from experience, leads to very poor handling response should you need to avoid some type of structure all of a sudden as you are idling into a shallow cove, etc... With the engine still in the running position, but cranked all the way up on the jackplate, I still have rapid response from my outboard in that situation. In addition, I've adjusted it down a bit on a rough water ride and turned a bash fest into a semi-normal feeling transit.
If you never worry about either of those things, then yes - the hydraulic will probably not be worth it for you. Manual plates also allow for a stronger base for high performance engines. Once they are locked down, they are solid. Not so with the hydraulic, as you will always have a slight bit of give due to the sliding surfaces needing room to move.
As Mini pointed out, Bobs Hydraulic is probably the best on the market. I don't know about Atlas, as I've never had the opportunity to use one, but I've heard many reports that claim they are awesome. They look really well built.
My preference on manual plates is defintely a Rapid Jack. Lots of others use the same design - a big ol' long screw that goes through the plate. More often than not, when adjusting those, you need to wiggle the engine a bit to get the plates to slide as you are loosening / tightening the big screw. I've seen a few people that don't put anti-seize or lube of any type on that screw, and they end up gauling the threads. The Rapid Jack is different. It has a large ratchet on the port side that you put a socket wrench on. You put pressure on the ratchet head with the socket wrench, and lift a little lever to allow the plate to go down. To go up, you simply need to crank on it and the lever will go over the ratchet, holding it in place. It adjusts in 1/4" increments, and it is a cable system that lifts and lowers the plate. I had one on my Cajun bass boat, and I could very easily adjust that plate on the water. I don't know of many people that can claim to do that easily with the other design.
All the best,
Glenn