Hi, Beth,
You are right that the Butterfly has a tall backrest, but you need to also note that it is a TRAVEL stroller and as such, it is narrow and overall not roomy, really. If we're talking about travel strollers only, then yeah, the Butterfly or the Joolz Aer+ ae your best bets. However, if we're talking everyday use strollers, you need to look not only at the backrest height (it is important but not as much) - but mostly at the overall space distribution plus space to the canopy. As I found, the non-reversible Baby Joggers are some of the roomiest strollers out there, and I personally would get a City Mini (GT) line model in a heartbeat if I needed space. Also, the Valco Trend is a superbly spacious stroller and I can recommend it for a tall toddler.
Truly, the width and overall distribution of space (including seat depth) will be just as important as the backrest, so perhaps try the strollers out before only deciding based on the backrest. I can strongly recommend the BJs or the Valco for a tall child, it will last and will be comfier that the tiny Butterfly.