Here's my thoughts on each Wheel:
Pegasis: Frankly, I have never been all that impressed with Pegasis. I don't know why, but it feels way too recoil-y and ineffective. I almost never use it.
Lightning: Lightning is glorious. It very much deserves its spot on the tier list.
Omega: Very, very strong against a wide variety of heights. Omega and Lightning, are, IMO, the perfect example of a great Attack type. They both handle opponents at a wide variety of height matchups well, and have a huge amount of Smash Attack.
Gravity: Really, really good. Still should be banned; the dual-spin combined with its great Attack is pretty game-breaking.
Beat: I don't really know about this one. I have no personal experience with it, and since the majority of the testing out there is fabricated, I can't cast judgement on it right now.
Jade: I believe TBD put it this way: Jade is rather inconsistent, but when it does hit it hits
hard. It's certainly good, but it has some issues with dealing with anything taller than itself. Probably not quite top-tier worthy, but close.
Screw: Bleh. It's only really effective when it can make use of its Upper Smash, and I wasn't really all that impressed with it when I tried using it on LTAC. It suffers from the same issues several of the other Wheels on this list have: ineffectiveness against certain other heights. If it is to compete against the likes of Omega for a spot, it had better do really, really well against one set of heights or do well against a wide variety of heights. Screw does neither.
Vulcan: I've had a lot more success with Vulcan. It still is pretty much completely ineffective against anything shorter than itself, but it does okay against things its own height and is more consistent against taller opponents. I used a Vulcan LTAC quite effectively at the GBT2 qualifier I went to. Vulcan just feels
right to me; it handles recoil admirably, has fairly good Stamina for an Attack type, and still has a very strong, consistent Upper Smash. I'm still not sure if it deserves to be on the top-tier list, but if Beat turns out to be a dud, I think Vulcan has a good chance for a spot.
Cosmic: I have no experience with this Wheel, though I see its main rival in the running for top-tier to be Jade; they are both Force Smashers for the most part, and if one turns out to be better than the other, then only the stronger one will probably make the list, due to their similar roles.
Phoenic: I was disappointed by Phoenic when I tried it out; it is really, really recoily in either Crystal Up or Crystal Down modes, and although its Smash was fairly good, it wasn't great and the recoil issues outweighed the usefulness of the Smash it had.
Wyvang and Balro: I haven't really tried either of these Wheels out yet; I used Wyvang a little and was fairly impressed, but I don't really use it at all (not for any particular fault or reason, I just don't.) I haven't tried Balro at all.
Dark Knight LTAC: I've been pushing this for a while; I really think it deserves a spot on the list. The offensive power that Ronin/Dark Knight can put out is crazy strong and still fairly consistent. Being left-spin, it also has a slight chance of straight-up OSing its opponent by spin-stealing, and it counters Meteo and Lightning combos by being the same spin direction as them. I tried making a Balance combo using Dark Knight on an LTAC setup, and adding what LAD I could by using Genbull instead of Girago, and even that did a good job as an Attack type. A more Attack-specialized version would do even better.