What you gain on the swings you lose on the roundabouts in this game.
Your own personal financial circumstances and motivation to fly are the easiest ways of answering the question.
Play safe and take the high retainer to afford some peace of mind in the winter?
Or...
Go balls out and reap the higher pay in the summer by flying your backside off?
Once you have over 1000 hours in the logbook I defy anyone to say they still have that same high motivation to get in the air, especially if an airline job is their ultimate aim. In my short time as an instructor I have learnt to spot the tell tale signs of battle fatigue a mile off!
I opted for the risk averse option from day one.
VFE.