If you're looking at a HBB for a 54" kid, I'd stick with only the tallest HBBs. She's probably outgrown the shorter HBBs, like the Evenflos. There are some very tall HBBs like the Safety 1st Boost Air that require vehicle head support and do not latch. For something that does not require vehicle head support and does latch and is still on the taller end, you could look at the Britax Parkway SGL or Recaro Performance. The Diono Cambria may be similar height too, but I'm not certain. My personal experiences are mainly with the Britax boosters, both the Parkway SGLs and the Frontiers in booster mode. HTH.
My 8yo still prefers HBBs. I had assumed backless because that seems to be what many people do.