E.O.
As far as I am concerned they are all pretty much the same. Some have more bells and whistles, but they are basically the same and must all meet certain safety standards. I think you should go with what best fits your kids and your vehicle. My daughter was in a booster seat until she was about 8 or nine I'd say.... It converted to a booster seat from a 5 point harness. I have lost the 5 point harness though. My 4 year old uses it now, though I myself have been looking to replace it with a booster seat booster seat that my 3 month old will be able to use once she gets old enough.(yeah i know... she is only 3 months old). but I always look at things in those terms.
My advice to you would be maybe to look online at reviews for booster seats at places like walmart and other stores where people can leave feedback. maybe do a google search for booster seats and see what you find. I just got a basic one that had a cup holder that pulled out from the seat. It worked fine and still works fine. I had to buy it after they changed the car seat rules to make my then 5 year old have to be in a booster seat and I was using the other aforementioned one for another child. Doesn't need to be anything special.... just look at them and see what looks good for you. good luck.