Well, I haven't seen them all, but here's what I can tell you...
UC series/OVA
079 - It's not bad, hell, it's pretty damn good for the late 70s. Obviously it won't be great in regards to action since action animation in anime has improved dramatically over the years, but it does have one of the better stories of the Gundam universe.
Zeta - This is the sequel to 079. In my opinion, it's one of the best series in the franchise. For it's time, it's animation is incredible.
ZZ - Sequel to Zeta. THIS SUCKS! I'm not sure if you want to watch this since it is the prequel to CCA, but if my memory recalls, it doesn't tie in to CCA particularly well...so you can probably skip it.
CCA (Char's Counterattack) - I'm on the fence about this one. I don't know if it's amazing or just mediocre. I watched it immediately after ZZ because I needed SOMETHING to get ZZ off my mind. Well, the thing I hated about it is that I didn't find the ending of the anime particularly well executed. I wasn't even sure what happened. I've only read theories about what happened at the end, it was so vague. Amuro Ray (the protagonist from 079) comes back as the protagonist of this one. Whether that sells you on watching it or not.
UC (Unicorn) - Honestly, I've only seen the first two episodes. However, chronologically speaking, it does happen after CCA in the UC universe. The first two episodes were pretty damn good...just haven't gotten around to watching the following five episodes yet.
Other series
Gundam Wing - I keep hearing people saying this is amazing...and to be honest, I watched about 30 episodes but I had a hard time with this one. I just couldn't give a shit about Heero. He was such a bland, uninteresting MC. I'm sure I'll go back and finish this someday, but God, I just couldn't get invested in the characters in this one. Plot wise, it is one of the better ones, but I have a hard time keeping an interest in the series if I can't get invested in the characters.
Gundam X - This was okay. It isn't the most amazing Gundam series on the planet. Hell, I think it actually has some of the better mech designs in the Gundam franchise. It does have kinda of a sweet romance to it (albeit it didn't finish as strong in that department as I would've liked).
Gundam Seed - As much as a lot of Gundam fans would chastise me for saying this, but I would have this a little higher on the "recommendation" list than most. Gundam Seed, for me at least, was one of the most enjoyable in the franchise. For some reason, it's the anime series I've re-watched more than any other anime I've ever watched. Then again, I like a nice romance and pretty visuals. The bigger problem with this series is that it likes to "recycle" scenes. It didn't bother me so much, but I did notice it's a common complaint.
Seed Destiny - The sad part is, as much as I loved Seed, I CANNOT recommend this. Destiny is one of the most loathsome Gundam series I've ever watched. Then again, Shinn is one of the most unlikable Gundam characters I've ever seen. Hell, he actually makes Heero seem like a likable main character with a fantastic personality. The good news is this series does get a little bit more tolerable later on when Kira sort of reverts back into the MC role, but it doesn't improve enough to save it from being a really bad anime.
Gundam 00 (including 2nd season) - Again, one of the better Gundam series that I'd highly recommend. It's highly political, highly dramatic, visually stunning. It was just an overall enjoyable series. Setsuna can be a little bland, but they at least develop his character a little and his backstory actually makes sense as to why he might seem a bit cold and disinterested.
00 Awakening of the Trail Blazer - Personally speaking, this movie sucked. I mean, REALLY sucked. It basically turned the "politically" driven Gundam franchise and turned it into an "alien invasion survival" anime. That doesn't fit the Gundam mold well at all. Not to mention it basically flipped a big middle finger to EVERYTHING the original 00 series built up. Yeah...let's just say I'm not fond of it, so I can't recommend it.
So I'd categorize it like this...
Watch
079
Zeta
CCA (barely, it has it's moments)
Unicorn (from what I've seen)
X
Seed
00
Maybe
Wing - I'm not the foremost expert on this one. Seems like some people love it and some people think it's bland...I'm in the latter department.
DON'T
ZZ
Seed Destiny
00 Awakening of the Trail Blazer |