Ok, old Yotsuba&! from ADV, or New Yotsuba&! from Yen Press. If you have some volumes from one company, and some from the other new release, do you try and replace them or just buy the ones you don't have?
Personally I'm in what I call the "hybrid" camp where half of my Yotsuba volumes will eventually be half and half from each licensing company. Maybe some Yotsuba Revoltech figure pics will improve the comparison with her standing in between the two versions of the manga volumes as I acquire them.
What are you going to do with your old ADV Yotsuba volumes? Sell them, keep 'em, use them as lending "taster" copies to get your friends hooked on the series? It's a dilemma, and we're discussing it here.
keep the old, buy the ones I don't have
I don't care about consistency since I have other things to spend my money on than trying to get the complete Yen Press set. So I'll keep my old ADV versions and buy the Yen Press ones as they come out.