That is the question. There are so many brands and types. It looks to me like symmetrical would be better but I don't know.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

Symmetrical is better for trucks with utility bodies, to help support the heavy rear. For cars, asymmetrical is better because there is more support where there is more weight, and more clearance for the vehicle doors.

I have an asymmetrical Rotary lift and it is working out great. I only work on cars. I don't have any trucks. My lift has 10,000 lbs. capacity. The lift I have is the same one used at Porsche and Mercedes dealer.

What is very important if you want to lift nearly any type of car is to get the three stage front arm with the flat top screw up pads. This configuation allow lifting cars with ground clearance as low as 3 1/2".

I've got an asymetric 7000lb lift and it lifts pick-ups fine. The asymetric arms allow the doors to open while the vehicle is in the air.

Based on your replies and my research I am considering this one:

http://www.dannmar.com/products/two-post-lifts/D-10AC/D-10AC_Data-Sheet.pdf

However, it does not have the 3 part front arm or the screw adjusters. I think it is a Rotary knock off except without those options. It has a minimum clearance of 4" not 3.5".

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

I copied what appears below from Rotary. Basically with the three stage arms you can lift just about any car out there and that lift with three stage arms can lift up all Mercedes vehicles.

"In order to safely raise a vehicle using a two-post surface or inground lift, it is critical that the lift arms make contact with the vehicles designated lift points. Failure to do so can damage the vehicle and put the technician at risk. On some vehicles, especially those with shorter wheelbases, wide vehicle track widths and/or low profiles, the recommended lift points can be difficult or impossible to reach with standard two-stage lift arms.

Rotary three-stage arms have three telescoping sections, providing a greater range of extension and retraction than any other lift arms. As a result, they can reach a broader range of vehicle pick-up points. This increased arm sweep has made the Rotary Lift three-stage arm package the preferred lift application of many vehicle manufacturers.

Some of the manufacturers, including Honda and VW/Audi, are insisting that their dealers use only Rotary Lift products with three-stage arms, says Mark Fitzpatrick, Rotary OEM account manager. They count on us to insure that their dealers have the right products to lift their vehicles safely.

Standard lift arms do not retract inward far enough to reach pick-up points on the Corvette, Cadillac XLR Roadster, Saturn Sky or Pontiac Solstice. Technicians at the GM Service Operations Garage in Warren, Mich., confirmed that the SmartLifts with three-stage arms installed there can properly lift these vehicles. Extensive testing has also found that only three-stage arm lifts can pick up all Mercedes-Benz vehicles.

Lifts with three-stage arms can improve technician flexibility by enabling them to move from one type of vehicle to another, such as from an SUV to a compact car, without making a lot of adjustments or having to stop and re-spot the vehicle."