Radian R100, Radian R120, or Radian RXT?

[Mommyof2Blessings]

I know that I need a Radian car seat to fit between 2 backless booster seats in the back of our GMC Yukon, but I'm not sure which one to get? My daughter that will be in the seat is almost 4 (April 9th). She is 32lbs. and 39" tall. The new baby will be in an infant car seat and our other little guy(2 when baby is born) is in a Britax Roundabout. The baby will move to the Roundabout and the 2 year old will move into our Graco Nautilus which the 3 year old is using now but won't fit between the boosters in the back. I was thinking I would get the Radian RXT mostly because I love the colors, but now I'm wondering if I could save money and get one of the other seats for her? What do you think?