In my opinion...
Firstly, DIN fittings are undoubtedly more reliable than Yoke. A couple of other advantages being: you can easily and cheaply adapt DIN to Yoke, DIN can be used with higher pressures.
This was my reasoning originally for purchasing a reg with DIN 300 fitting.
However, I found that the vast majority of dive centres I dived with only offered tanks with Yoke fittings (Across Australia and Asia, I can't comment on USA).
I found the use of a DIN to Yoke adapter VERY annoying. It resulted in my head getting constantly bumped on the reg due to the extra protrusion it added. I now dive with a Yoke fitted reg purely for this reason.
So a point worth considering I think. I would suggest you try to establish where you are most likely to be diving and find out which system is commonly used in these areas.
With regards to choosing a brand of reg, personally I think you get what you pay for. Set yourself a budget, find several regs you like the look of and that are brands you feel confident with within that budget, then research the shortlist until you can make an informed choice.
When I bought my first full set of regs, I eventually shortlisted 3 sets, my final decision was based on their weight for traveling.
Hope this helps...