To start things off, here's my list:
1.
Zanneck
The Zanneck is easily my favorite mobile suit in the Gundam shows. While its technical details aren't all that special, it's the way the Zanneck is presented that's especially flavorful. Perhaps unique to all of the Gundam mecha, in the episode where we first see the Zanneck, we don't get to see the pilot - instead, all that's depicted is the sound of a bell. Combine that with the way it manhandled all the enemies arrayed against it, and the entire sequence provokes a sense of menace that I have yet to see recaptured in a Gundam show.
To top it off, the Zanneck itself is a very flawed mobile suit: it has a huge gun, but it can barely move on its own, and has to rely on its platform for propulsion. It's only thanks to (probably) the skill of its pilot that it can hold its own against supposedly far superior, and vastly more maneuverable V2s and Gunblastors, especially when the fight gets to melee range. All told, while the Zanneck doesn't show up all that often, the strength of its initial appearance is a big contributing factor as to why Victory Gundam is my favorite Gundam TV show.
2.
V2 Gundam
This is plain jane V2 without any of its add-on equipment is my favorite Gundam. I like the clean lines and color scheme of this mobile suit, but again, it's the presentation that shines. Normally, I don't like the idea of gattai units, but V2 at least employs this feature in a way that (sort of) makes sense. Instead of just combining to beat the enemy, it also uncombines all the time to provide all manner of tactical advantages, from escaping from enemies to using body parts as makeshift bombs (who the heck needs munitions
).
A lot of these features are shared with regular Victory Gundams, but the V2 also has the original Wings of Light technology/propulsion. This latter is a broken technology in the sense that it also makes for top-end defensive and offensive capabilities, but it still looks darn cool and makes for a lot of creatively interesting visuals.
3.
Leo/Aries
There's nothing remarkable about these mobile suits, but they give off the feel of utilitarian line mobile suits. I really like the idea of no-fancy business, capable designs that are straightforward general combat machines. If humanoid mecha are really ever designed, this is one of ways they'd look. I'd put the Zakus here, but they don't seem to give off the same feel, and I've never really warmed to them.
It's a real pity that the creators of Wing decided to treat these mobile suits like Fokker fodder...
4.
Dom Trooper
The Dom Trooper is here for purely aesthetic reasons. I never liked the look of the various UC Doms/Dom-lookalikes; but I find this redesign very appealing. Easily my favorite Cosmic Era mobile suit. In term of overall looks, only Launcher Strike Gundam (not the other versions, mind you) come close to being as appealing to me.
5.
Tieren
The Tieren is in the same boat as the Leo/Aries units. It's a solid-looking clunky design that gives the feeling like the developers had a clue as to how war machines are supposed to look. The only thing that I don't like about the standard model is that the wrist-mounted gun looks awfully flimsy. It's also too bad that the Fokker fodder syndrome shows up here as well.