Guys what should I take to get best roi ?

zotac 1060 mini 6gb for 332 USD
palit geforce 6 gb storm for 324 USD
or
zotac 1060 3 gb for 239 USD
gigabyte 1060 3gb windforce (dual fan) for 249 USD
palit geforce 3 gb stormx for 250 USD

which one are the best to overclock ?