Here's my take, for what it's worth...
Given your present logbook (assuming as you say you are a greenhorn and MPL, your hours and operational background at the moment are mostly in your future and not in your past), I would go for the Dash instead of the Airbus. Let me elaborate....
First of all, your personal reasons for commuting will always go ahead of anything else. Is it possible for the same personal reasons (family I'm guessing) to relocate? How about in 2 years from now? Only you know the answer to these questions.
Anyhow, between the 2 airlines, as you are an up and coming airman, being in a situation where you actually can choose between 2 employers, always, I say again, ALWAYS, go for the stable, legacy carrier. Now, before everybody slams their touchscreen keyboards, consider the longterm career. Yes, the path to the left seat will take significantly more time. Yes, your longterm pay will be (probably) less than a rather quick upgrade with a new, smaller carrier. And yes, you will start on what is by many considered as an inferior type. However, all this falls behind a few things. First of all ask yourself, as a newbie, if a union could be a positive thing to be a part of? Could a seniority list be something that gives you foresight? How about payscales, retirement plans, roster stability, certain other benefits that have already been negotiated for you? And guess what.... Flying a turboprop, with shorter sectors (more departures and approaches) actually hones your flying skills (albeit the automation is well applied). The Q400 is also appreciated by an increasing number of airlines who now are hiring, so I wouldn't be worries about that. But how about the AUA fleet? A renewable 2 year contract with AUA might just place you on another type within a few years anyway.
But at the end of the day it's a personal choice. I have never flown for a lowcost carrier, never been on a contract or had to worry about the things I read about on pprune. Never had to worry. Crew on that for a little while. The "downside"? Still FO at 40.... On the otherhand, pay, roster stability, benefits (pension plan) and lifestyle easily outweigh flying the mediumhaul jets around the European circuit. BTW, since I fly the small Dashes, I'm completely biased regarding types
Choose the one which you think will make you happy, and adjust everything else accordingly. But could you let us know your choice, and your reasons, once you have made it?