I'd have to say the winged lion. While I was very hesitant to loot for it and it took about a month to do so. I slightly regret but same time I don't. I'm more for the quality use of the mount rather than appearance. The mount allows me to have someone with me so I can transport them. Allows to go on water. All for all its about as useful as a mount gets. Reason I somewhat regret getting it despite how useful it is. It's the fact that I rarely even use mounts. I'm that one weird guy that pretty much forgets mounts exist even as they fly past me and I'll walk from onnet to destiny to see the bazaar.