Steve Lynch's booths are the industry standard. His software is way easy to use, and he gives outstanding support (you get his cell phone).
The booth was designed by the very same guy who has to hump it in & out of trucks & venues so I doubt you're going to find a better design.
As far as price, Steve's prices are way more than fair, and will blow away the prices from competitors if one can honestly say he even has any.
Steve has more than a few models and features to choose from. MBLV is on this week so he may be hard to get a hold of.
Call Stephen Lynch @ 404-934-4030 to have any and all of your photo booth questions answered.
The Atlanta booths looked great at the Mobile Beat show. He has a few designs depending on your needs. You should see what your competition is doing (open style, booth style, standing or seated etc) and pick a booth that is as unique as possible for your area.
I have Open Air Booths and they've been great. They are a bit uglier than Atlanta, but they perform as advertised and the service has been fine.
I bought a Kingdom but I don't recommend them since you have to continually buy codes to enter into the software to keep it running. If you don't buy codes, the software locks you out. I could see this if the booth were heavily subsidized. But my booth was around $11k. It had $1800 in components and $1500 in metal work to make it look pretty much like a copy of an Apple Industries booth. They say you're paying for the software, but their software is not any better than an off the shelf solution you could buy for $175. The only reason for custom software is to lock customers out of the software if you don't buy codes.
Disclaimer: Kingdom may have changed their scheme in the last few years since I bought mine. My information is based on my experience.
I also have a photo booth from Steve Lynch and decided to put my extra touch to it by surrounding it with pipe and drape enclosure and throwing down a red carpet with rope and stanchions. It definitely gives it an elegant appeal and that has been very popular with brides and quinceaneras!
I may add that you need to question yourself "How will I be transporting" the booth. APB with all the accessories need a cargo van and bigger. I have a pathfinder and my big booth won't fit. If you plan on hiring people to use your booth...you need people with a large capacity vehicle or trailer. I have 2 APB but man i wish i could toss all the stuff in my pathfinder and go rather than driving my 17 year old van that gets 10mpg.
I use the CSL booth simply due to the form factor. I can fit the booth into my one truck with whatever sound and lights I'm also bringing for the event. Other booths do not afford me this freedom and flexibility.
My cousin fit my entire booth, ez up booth, props trunk, table and all the other accessories into his Camry last weekend, (and still had the passenger seat open for his girlfriend)
When I roll in, the entire system fits on my Rock'N'Roller R-6 Multi-Cart!