I been doing the same research about the a series for months now.ther really isnt much difference from the first a5 compared to the new a3 ( 2016) other then the slightly faster processor.
However the a3 has a smaller screen, slightly more ppi, lower ram ( 1.5Gb) and much higher priced in my country. I would still go for the first a5, I made a big mistake in the past for going for a phone with a better processor and lower ram and paid the price. nothing lower then 2GB of ram for any new phone you are thinking of buying I would say.