Go for Monarch if you want good trips in a company that is extremely stable. Scheduled services are always expanding, the aircraft fleets are growing (especially with the introduction of 6 Boeings 787's in 2010!!!)
I left Monarch to go to a scheduled airline, but I sometimes regret leaving. You hear stories about senior crew being strict at Monarch. Experience has shown this is very much exaggereated. If you follow the rules you'll be fine. I miss flying on "bendy" 757's!