8 or 16 ohm?

I have a DIY 2x12 cab that I'm going to put a V30 & ET65 in.  My "pexi-ish" amp has 4, 8 and 16 ohm output.  Not sure if it really matters what configuration I use for the speakers as long as it matches the amp.  Any advice on whether I should buy the 8 or 16 ohm speakers?

Go with two 16-ohms in parallel - for a total cab load of 8-ohms. That'll be your most versatile and fool-proof option.