EK-FC1080 GTX Ti - Nickel!!!!
Full custom loop = extreme overclock + quiet + cheaper in long run (re-usable for different upgrade) + higher quality in parts (leak free) + more flexibility.
I would go for a AIO or hybrid any day of the week as they run cooler and quieter than the fan cooled brethren. Never have had any of my AIO cooling options ever leaked. I have had to replace one because the fan on the radiator started squeaking on an early model. The radiator fan combinations these days are easily replaceable vs the earlier models.
I have 3 1080 ti SC2 hybrids in my render machine and I love them. The chance of leaking is so small its not even worth considering. These perform wonderfully. Never gets above 40c under full load.
Bad as in leaky, or bad as in doesn't OC well? Because anything that will leak is not an option for me. That is why I have always gone air cooled on previous builds. I don't really have the money to leak water all over my PC. A performance per dollar issue is less consequential than an actual stability issue.
In fact gamer nexus benchmarked a couple of the cards on the list an it seems they can handle pretty good overclocks and with a little of diy it is plausible to make a little custom loop from an aio, (not sure if this will work on a gpu aio) but a good air cooler on the card is also a good option