Monarch is a good stepping stone. You will get good training and fly with nice people.
I am looking to leave (Capt A320). The current management do not give a sh1t about its pilots and life is only getting worse. The union is well represented but unfortunately there are two different lifestyles within the company; A300/B757/A330 pilots are generally happy and do not want to rock the boat, A320 pilots are miserable - so any decision to stand up to the company is based on your fleet and to a certain extent, base. I sincerely do not know whether those in a better position are prepared to stand up for those of us who are not. I expect time will tell.
My advice is that we are a better bet than some (flybe, XL, ryanair etc) but a lot worse than others (BA, Virgin, Brits, First Choice, TFly, Easy etc).