I honestly would prefer to mine eth, as it seems the most safe coin to mine, plus it has gotten really profitable with the price surge, if you're buying amd buy rx 470s 4gb, they'll hit ROI much faster than rx 480 8gb, in some places nvidia cards have much better resell value so if its like that where you're living then sounds like a good choice. Also see how much electricity your gtx 750ti is pulling, it might be unprofitable if you don't have very cheap electricity.
Meh, if you get 470s, i'd wait for a deal or just take sapphire nitro+ 470 8gb. Mine do 29 on eth, 750 on monero. They do as good as 480s if modded properly.
Sapphire because dual bios :-)
The 4gb versions are ok but i'd go for nitro+ only, this way you're sure to get samsung memory and not crappy elpida or hynix...