I'd definitely prefer the foreign one.
As for which ones, these are the ones I have over on 6th gen, in a dream ball unless specified otherwise:
Cottonee, Ekans, Paras, Pinsir, Eevee, Snorlax, Heracross, Chansey, Shroomish, Slakoth, Nincada, Whismur, Plusle, Minun, Gulpin, Roselia, Cherubi, Aipom, Gible, Carnivine, Sneasel, Pidove, Roggenrola, Drillbur, Audino, Barboach (Dive), Tympole, Venipede, Petilil, Basculin (Blue in Dream, Red in Dive), Sandile, Maractus, Dwebble, Scrafty, Sigilyph, Tirtouga, Solosis, Ducklett, Vanillish, Emolga, Karrablast, Alomomola, Joltik, Elgyem, Axew, Shelmet, Stunfisk, Pawniard, Heatmor, Durant, Timburr, Kabuto (Dive), Omanyte (Dive).
As I said, I do have pretty much all of them, but the rest are still sitting on gen 5. You can pick from those too, if you have to.