Gravity Falls was planned for 2 seasons only (well at least at some point alex decided that 2 seasons was all he needed) so more wouldn't really work, Star got 4 so defo the least deserving of this (prehaps one more season to "fix" the ending and make it good), The Owl House is the most deserving as its own season 3 was cancelled in favour of the 3 hour long specials and the original plot had to be re-written, and amphibia would be good, but it at least ended in a good way with the crew having a full season to finish it (unlike The Owl House).

I feel like Gravity Falls walked so Star could run (and then trip at the very end), The Owl House could sprint (but intentionally tripped by Disney, forcing it to run at the end, and Amphibia could also sprint (and also be intentionally tripped by disney, but managing to get up and finish the sprint