joining CX isnt a life sentence. If you dont like it you can always leave. I guess the same thing could be said about CAL but the pay difference suggests it would be better to try CX first.
We have never really had any reliable roster bidding until the last 2 years. Even so, we are not building whole lines. You can bid for lifestyle choices, such as work stacking to get days off, or you can bid for specific trips. SO really not much control.
On the 777 or Airbus fleets, as FO or CN you will have great variety of flying as you could be doing tpe return one day and then new york the next. You can be based in the US/Europe/Oz/NZ if you want to and there are slots available. I think that variety keeps CX interesting.
At the end of the day, CX wants/needs guys and gals to get their command. From some of the bellyaching you read on PPRUNE you would wonder if anyone actually passes here! I dont have exact figures(unusual for me;-) but I know the command pass rate got much better in the second half of the year...over 80% I think?
I remember a QF mate telling me many years ago that they had a 100% failure rate for a while on their 9month command courses. So I guess can look to its oneworld partners when seeking "worst practice" changes;-)