All comments are IMHO:
Speed is the best coaster of the bunch, but considering the others, that isn't actually saying a lot. I liked it, but I don't find it amazing.
Canyon Blaster: One of the best Arrow loopers ever made. It's smooth and has a unique setting. It's still just a smallish Arrow looper when all is said and done.
Manhattan Express: (It still has signs that say that as of March 2009, so I still call it that.) I liked it. Is it a great coaster? No, but it's got a lot of interesting features about it. I never found it all that rough.
Desperado: This was an amazing coaster when first built. Now, with 15 years of development and progress, it's an example of the kind of lousy design that we as coaster enthusiasts used to think was quality. (Yes, this is an insult to Magnum inserted into a topic about Nevada coasters.)
Lightning Bolt was mediocre at best in both of it's forms.
High Roller: Never rode it, and for the same reason why I tend to dislike ALL of the Nevada coasters:
Way too damn expensive for what you're getting.
The one time I went to Vegas while High Roller was still in operation, it was @$30 to ride up to the top of the tower, plus $12 to ride the coaster. If you wanted a 'value package', you could have the elevator ride plus one go on each of the two rides for like $45. Yeah, no thank you. That coaster, if sitting on the ground would be the equivalent of a Rollerskater. I wouldn't pay $42 or $45 to ride a rollerskater, even now. (I believe it's cheaper to go up there now.)