B.H.
My opinion with boosters is they stink. My almost 6 year old doesn't sit well in one at all. She behaves and is mature but just doesn't fit or sit well.
A 2year old shouldn't be in a booster even being that large. A booster is for children a minimum of 3years but I'd even push it to 5 or older.
Alot of parents rush to booster's thinking they're easier and excited there kids have grown up. But car crash's are the #1 reason children die not from illness or anything else. If you do buy a booster Graco Turbo or Graco Airbooster's are the best choice. I do have one as a back up seat and it's nice but when my daughter falls asleep her head is in her lap and she's slouched and all over the place and is very unsafe.
I would spend the extra money and buy one of the following seats that will harness a child longer and isn't a booster.
Cosco Apex -65lbs/ Britax Marathon -65lbs or the Britax Regent goes to 80lbs. all using a harness and not a booster.
I have my almost 6 year old in the Britax Regent. She loves it and I love it and she's safe!
Here's a link to a awesome website where you can ask this exact same question and get some really good feedback from other mom's and carseat techs..It's a great website, you don't have to register or be a member to ask a question either.