I've gotten to know a few AC cabin crew over the years, including some with very high seniority who largely get to pick and choose the things they work. I think this is a very individual question that depends heavily on each person's preferences and life situations.

One SD I've flown with a lot doesn't like being away from home overnight. He wants the longest possible same-day turn from YYC. Historically, this has meant EWR (if the schedule was right), or a domestic TCON. But I also saw him one day on a trip to... PHX, I think? And he said that day it was because he needed a shorter pairing so he could be home for his kid's Christmas concert or something like that. This approach is very efficient in terms of paid hours of work per hour away from home.

A couple of other pretty senior SDs have told me they like to get their hours done in as few days of flying as possible. So that means working things like YYC-LHR/FRA, YYZ-Asia, etc. This is much less efficient in terms of paid work per hour away, but can require fewer days away from home. I seem to recall one SD telling me that 3x YYZ-HKG a month was all he needed, and then he might occasionally pick up a shorter pairing somewhere if he wanted some extra hours, but that he liked not having to do more than 3 round trips, 3 drives to/from the airport, etc.

Some do also have preferences on what type of aircraft they like to fly on. My experience, and something I've heard from a bunch of people within AC, is that the 7M8 crews often skew junior because most FAs hate working them. The galleys and the lavs are so cramped, they're pretty miserable to work. The 223s don't get much more love, but do seem to be preferred over the 7M8s.

Then there are those who like certain destinations because of the time spent there. For instance, I know the YYC-OGG route, back when it was mainline 763s, was a very high-demand pairing and often had crazy senior crews, because they all loved getting a nice day or two in Hawaii in the middle of winter.