Here's my 2 cents worth....
I've had both two post and four post style lifts for many years and it really depends on what they will be used for "most' of the time and the amount of workspace you have .
At home I currently have three CYTECH (from Wichita, KS) Model DP-7 7000 pound 4 post lifts, a 7000lb Benwill (from Carson, Ca) 2 post lift, a Bishamon 7000lb 2 post lift and a 10,000lb Bishamon 2 post lift (for heavy duty chores). All are top quality USA made products. I've never actually seen a Backyard Buddy in person, but the CYTECH lifts are well constructed with full length welds on all the support stops (unlike some other brands that I hae seen).
If your main purpose is to stack/store vehicles than the 4 post version is excellent. You can work on them as well, but in a limited capacity. I purposely don't have mine anchored in place which allows me to move them around with or without a car on the lift (with the optional castors). This works great for squeezing things in tight places or for moving a non-running vehicle outside to perhaps pressure wash the underside.......
I find that the 2 post lifts are far most useful, for both storage and vehicle work. The pricing is about the same, but you definitely have to anchor them in place so choose your location well. If I store a car under another for any length in time, I strap the upper car to the supports just to be safe (see photo). I've gone through several strong earthquakes with these lifts and have never had a car shift on them.
I believe you can find info on the CYTECH models at
http://www.doublepark.net if you interested in checking them out.