Miltank is better. She's not only defensive, but she's physically strong and fast! Add that Defense Curl, Rollout, Milk Drink or any other good Physical move and she will rampage against any Pokémon there!
Chansey is an amazing wall due to hp and evolite (in later gens). But i like Miltank better for ONE reason. Whitneys miltank, shows, if used correctly how much of an annoyance it can be for the unprepared. And its a cow
My Shiny Pokemon:
Greninja ;Volcarona; (X2) Aegislash ;Lampent; Diggersby
Luvin' the t'wigs <3
3DS fc: Paddy 2621-3316-5077 (Pm if you add me)
I would say that Miltank is stronger, but I'll go with Chansey because of its defenses/healing, plus it's cute. :P
Miltank looks better, and can learn cool moves even fighting moves, thats cool for a normal type) And it looks like a cow. What does chansey look like ? an egg.