Which of the below card is best for long term GPU mining and what coins you suggest to mine with each of these cards.
MSI 11 GB NVIDIA GTX 1080 Ti
ROI per nicehash : 9 months
MSI 8 GB GTX 1080
ROI per nicehash : 6 months
Can only say few words about the two above: don't go for 1080, choose either 1070 or 1080ti. Besides, check exactly which model of these cards you're buying, same brand 1070's, for example, may have 4-5 models all varying in clock speeds => mining efficiency.
Are those GTX 1080 really that bad? Because price-wise I can buy 1070 for $520, 1080 for $575 and 1080Ti for $825.