L.M.
When I did my research (almost two years ago) to transition my son from rear-facing to forward facing, the Graco Nautilus offered the highest weight allowance for the five-point harness (60 lbs) and then it converted to a booster seat to up to 100 lbs. Best bang for the buck, then. There may be some on the market now that tie or beat that, but I don't think you can beat the price of Graco.