Subject says it all^ (the pc will be used for gaming) NVIDIA GeForce GTX 1080 - 8GB (GDDR5X) (VR-Ready) and NVIDIA GeForce GTX 980Ti - 6GB specifically
founders edition is basically the "reference" version of the card. so its quite pointless to get them really since they cost $100 more. and offer no benefit, and as ive seen from people who have the founders edition 1080, the cooler is quite bad. so yea better wait for the custom versions of the 1080 to your liking.
and the GTX 1070 is a whole new card it self. a nerfed version of the 1080. but quite a powerful card, more powerful than the Titan X/980 Ti.
people are saying that the 1080 preforms better than the 980ti and they are mostly correct, the 1080 utilizes newer technology and will beat the 980ti hands down in modern games, but when you look at older games and indie games that dont use the newer technology then the 980ti beats the 1080