Which ring to buy

Hi so thing is my friend has 3 rings abd selling me for these price

Gabit - ₹5k (slightly used and only 4 month warranty left) . Fittr hart x2 - ₹6k (1 week old and used 1 time) . Ultrahuman air - ₹9k (unboxed and only 2 month warranty left)

He is willing to sell me one but idk which to buy so can anyone recommend me which one should i get abd why is it better