Which ever is the cheapest, on sale etc. As a user, not pushing OC boundaries, you'll not notice any difference in the cards. Only benchmarks or synthetic tests will. If a game shows 101fps with 1 card, and 103fps with the other, even on a 144Hz monitor, its physically impossible for the human eye to see the difference. On a standard 60Hz 1080p monitor, both cards will be capped at 60fps, so any performance bonuses are negated anyways.
Buy the cheaper card.