I got a commercial Benwill 2 post asymeteric below. I bought it used from my buddy's shop and all of the seals had just been changed on it. Most lifts use very similar parts and can be serviced by almost any general lift service person, many of the parts are interchangable.
The only things to consider are lift height if you are tall, needs to go about 6' up. And whether or not you want the ramp type like Grumpy has or a post/arm type which allows easy wheel changes but is harder to do mods that require the suspension to be loaded, although I have some ingenius ways to do that with my lift.
Here's a place I found to be very helpful
http://www.autoliftrepair.com/ they sent me a full manual for my lift and I didn't buy it from them.