- Physical Lift Size: The four post is much more bulky so would require more room. I'd give this one to the two post.
- Storage Capability: Most of the photos of the four post lifts I see show a double stacking of cars. I suppose you COULD do this with a two post, but I'm not sure this is one of the intents for two. I'd give this one to the four post.
- Versatility: This is where I have my biggest beef with a two post. What I don't like about the two post is the ability to do work that requires the car or truck to be on all wheels so the suspension is loaded. For example, my Impala is lowered and I want run new exhaust over the rear axles to put some bellfowers on it. It will be difficult on the two post because there is no weight on the rear axle so I don't really know how much room I have to play with. I usually end up doing this type of work with a floor jack and jack stands which DEFEATS the purpose of the lift! Another note here, you can't pick up air ride equipped cars or trucks unless you secure the suspension up. My squarebody C10 is on air ride and has never been on the lift for this reason. One last quick note here, lifting X-frames cars (like my '62 Impala) is probably not recommended OR is a pain because the arms don't reach the frame. I have lifted mine using the pinch mold and made extra sure the safety jacks were secure but this is probably not the best idea. I give this one to the four post.
- Use: A slight pain in the butt aspect of the two post is having to bend over or kneel on the ground to line up the arms with the jack points of the car or truck. Also, eyeing up the center of gravity of the car or truck can be tricky and takes a time or two to get them positioned right. You know you have the car COMPLETELY balanced prior to lifting or BAD things can happen. At least that's what the sticker on the post shows. I'm sure you get the picture. I give this one to the four post.
All that being said, our lift has been GRRRREAT! It has made SO many other jobs easier to complete. I, however, don't really care to use it for a simple oil change though. It's just too much extra effort to have to get the car positioned, lifted and secured correctly for a 15 minute oil change job. You see on TV shows many places have both types, but if you can only have one, I'd say get a four post. Again, this is just my opinion based on my personal experience. Feel free to chime in and add your experience or thoughts on the topic.
Oh, one last thing, all your friends will want to use it.