I have so many dream mounts its insane haha.
Ground:
Raven Lord: The first mount I really though 'OMG NEED IT' for. Done over 200 runs without a drop, but hopefully if I'm patient enough it will eventually show up and join the rest of them.
Zulian Tiger: Once I started ZG runs I realized I HAD to have this mount. It's so gorgeous because of the colouration and the model, and as Horde it would be a real prize to get. Luckily I got it a few weeks before they removed it from game, so I'm very very happy about that.
Black Warstrider: Seems kinda silly for some, but when I hit level 60 back in BC I really wanted a hawkstrider mount. I PvP'd my ass off to get enough BG marks so that when I dinged I could buy the pretty black chicken. It was my first mount that I obtained other than my racials.

Not so much a dream mount anymore but it was back then.
Mechano-Hog: What is more badass than a bike? I saved up enough gold but didn't get one crafted because my goal was to not drop below 10k. However, my amazing boyfriend surprised me with one last week for an early Christmas present! <3
Woolly Rhino:: My luck sucks and I can't justify spending over $100 on a mount.. but I would love to have the rhino! I also would love the spectral tiger or chicken mount, but I doubt they will happen either.
Flying:
Time Lost Proto Drake: Proto-Drakes are one of my favourite flying mounts. I love the model so I knew I had to have at least one. Now I have the red, green and violet, but I really, REALLY want the time lost. I am such a trophy hunter and the colouration on the mount is just gorgeous. I've been parked up there and I actually missed it by a few minutes last night because I had some chili... hopefully it will turn up eventually, I want it soo bad.
Drake of the Winds: I don't really care what colour, though I really like the red one. The models are so beautiful! But I won't be getting any of these on my collector until I get a TLPD, so it might be a while until I get one.
Twilight Drake: Such a gorgeous drake. Never thought I would have it but I ended up getting into a pug and paying the winner 7500g for it. Totally worth it, so pretty!
Red Dragonhawk: I set a goal for myself to get 50 mounts and I didn't think I could do it. Now over 2 years later I'm sitting at 118, and the dragonhawk is mine. As I said I am a trophy hunter and mount collector above all else in the game, so having this mount is a huge accomplishment for me.