Just four letter: YMMV

Lots will depend on the road condition of your route, your weight and load you are carrying, how many hills and so on.

What I find better for me might be different for you. My road are all street road and mostly smooth enough to use 700x25. I'm light enough to go 23 if I want but with my load of my rack, bag, and pannier, I think a 23 might get out of round as compare to a 25 with the same PSI. If my road were rougher, than I may consider wider tire or even 26. Here is something to also think about, in a very steep hill, I can go faster and easier on a MTB 26 because of gearing and smaller diameter tire than I can on a 700 with the same daily load.....but on my light carbon bike with no load, I fly up those hills like a goat.

Confuse yet? Best thing to do is try different setup of bikes if you can so that you know what will be best bike for that route. Otherwise do the N+1 thing and you'll be cover for most scenerio.