If you are at the point when you feel that your chances of a job and your networking skills are getting you nowhere and you decide to pay for a rating then I would stay clear of the ATR. With Air Wales going tits up the opportunities in say the UK and Ireland are limited. Aer Arran have in the past taken people from Sky Blue but they have also failed a number of people during OPC's in the past few years. Fact is that they would prefer to interview you and put you through your paces in the 737-200 and then train you direct knowing what sort of person you are.
If you look at where the jobs are turning up at the moment it is on the A320 and 737 for self funded and non funded alike. Yes there are some jobs in the turbo prop market given that the jet operators are hiring like mad which tends to pull up the experienced TP guys. Outfits like GECAT are placing A320 guys like crazy with the likes of BMI, Air Malta, Aer Lingus and others. These usually come through recommendations and so you will need to impress them. 737 jobs are always available through Ryanair if you are desperate enough but as pointed out they require time on type or worse still if they take you on them you will have to pay for the rating again.