Like Carl, I chose a 10k pound model so I could get a wider inside column width mainly, plus I work on some larger trucks such as 4-door Duramax and Cummins trucks and wanted the capacity. The interior width was a small amount but every bit helps.
I also work on a lot of FWD cars so I waffled on a symmetrical vs. asymmetrical style of lift more than anything. I know most automotive lifts are built oversees and then some are assembled in the US and advertised as "Made in the USA", however, more importantly I only chose to look at lifts that are ALI certified. Reason being as in order to be ALI (Automotive Lift Institute) Certified the lift must pass a specific set of standards such as cable type, swedge spec's and safety locking mechanisms but more importantly they must be rated to safely lift and suspend 150% of the rated capacity. That means a 10k pound lift must be able to have a safety margin built in for 15k pounds. I knew it would not only be me under the lift but also my son and wanted that certification if nothing more than peace of mind.
I also didn't want a base plate design because I do a lot of suspension and transmission work and really didn't want that plate on the floor impeding my transmission jack or even my tool cart being rolled around. I know some people with ceiling heights don't have much of a choice but if at all possible get one with overhead lines rather than a base plate model.
Lastly I started looking at ones with the largest footprint at the column. My thinking was a bigger footprint meant more stable as it would not only spread the load out over a larger area but also the floor anchors would not be as close as a smaller column base.
With looking at all these parameters I decided I really wanted a Mohawk 10k pound 2-post lift. Mohawk is the only fully USA made lift, however, my budget was about a third of what those run. My next level down brought me to Atlas, Challenger, Ammco, Rotary and Forward brands. A buddy of mine has several of the Atlas lifts at his shop and he loves them. However, his biggest gripe is with smaller cars as all his Atlas lifts were symmetrical lifts.
I then went to a couple other shops around that I knew the owners of and started asking questions. My findings resulted in most everyone was happy with their purchases and no one was actually unhappy with any of them but it seemed they all had pro's and con's. One shop had just installed Challenger Versa-lifts which were a hybrid between symmetrical and asymmetrical style of lifts. They were very pleased with the 3-stage arms both front and rear as the symmetrically positioned columns but on really heavy vehicles they preferred to use there Rotary or Forward symmetrical lifts even though they were rated 1k pounds less (9k vs. 10k lifts).
I then stumbled across the Ammco 10k pound 2-post lift in a NAPA Real Deals ad one day and noticed they were also more of a hybrid design by keeping the symmetrical positioned columns yet equipped with triple stage front arms and dual stage rear arms thus allowing vehicles to be lifted in both the traditional symmetrical fashion as well as small to mid-size front wheel drive's lifted in the asymmetrical configuration and had very large mounting feet at the column bases. Upon further investigation I found that both the Ammco and the Challenger lifts came out of the same Dannaher factory and were quite similar and advertised as hybrids between symmetrical and asymmetrical lifting configurations. I ended purchasing the Ammco 10k pound 2-in-1 labeled lift on the NAPA Real Deals pricing and a co-worker of mine purchased the Challenger Versa-lift several months later as it was on sale at the time in the Real Deals ad. Both are quite similar but not sure if they are still made by Dannaher or not. I purchased my Ammco 10k pound lift back in mid-2011 so I have had it for over 10 years now. No issues whatsoever and still use it very frequently. There are times I wish I had a second lift in fact so I don't regret purchasing it.
Here are some pictures of my Ammco 2 in 1 10k pound lift being used to lift a variety of vehicle sizes and designs in both the symmetrical and asymmetrical manner.
Hope this is helpful.
Mike