Just to save others the heart palpitations--there were no new NMC textures uploaded on March 8, 2015. Still the packs from 2013; big note at the bottom of the page to point it out.
The Ojo Bueno files will appear all over the place just like NMC, in both wastelands and even in some DLC (not sure about Zeta e.g.). Naturally ones like the Novac pack won't go far beyond the city limits.
Like EnderDragonfire says, it's a matter of personal preference what you use. That and system specs of course. And like RoyBatty says, several are repeats. Best to know ahead of time what you're getting into.
If you have the hard-drive room to extract the textures (Ojo's are in FoMods already), I recommend viewing at least some of the key ones like dirt, rocks/canyons, roads, etc (in the Landscape folder). Things you're going to see all the time, all game long. I recommend choosing a full 'set' instead of a few tex from each pack per set. By 'set' I mean like all the tex of a kind (the rocks in Ojo, the dirt in NMC, and so on). Sometimes a mix-n-match combination can look really funky in game, but done just-so might possibly make a masterpiece. You'll know your own tastes better than anybody else.
Choose which texture set you like best, and answer yes/no (for overwrite) appropriately. Or, better yet--once you decide what you like, delete the textures from the set you don't want. Then make new install packs from what's left over. Then you can forget about all the brain-melting questions during install and instead go drink a Nuka-Cola (or maybe 3, long extraction) while the computer slaves away.
P.S: Saw the mailbox pic you posted--IMHO Ojo has a better rust texture than NMC (in particular his normals map). See for yourself! One of my favorites are his "Ultra" High-Res Autos--ultra grungy they are, just what you'd expect after a couple centuries/so.
