In this center, it's the one that stays here the longest, ends up PTS. Their age has no bearing in general.
This is why I picked this bunny as the female:
because she stays there since April, and the volunteer over here was literally begging me to pick her, because her time is up, if the center ran out of space, she is the first one to go. And she has great personality, and the only other female I like is this little girl:
which is yet another black color lop, so I figure if there are 2 lops, I can't tell which is which, so I might as well go w/ a different breed.
The volunteer also said that it is very sad after she get to know a bunny for 5 mth. (Hopper above), and then find out that she has to PTS due to lack of space. As such, Hopper is going home w/ me.
Anyhoo, going w/ your idea as to which one staying there for a long time, then I should pick Monty. Because as you can see from the browse button under adoption,
http://www.calgaryhumane.ca/
Monty was there since June 22, whereas Max was there in July 21, so if there is a new batch of bunnies, Monty would have to PTS before Max does, because Monty has been there for 1 month longer.