But I'd say start with either the original Gundam or with The Origin or Thunderbolt.
Where are these recommendations coming from?
The Origin builds off of 0079. It's an alternative timeline that doesn't feed into any other UC media. There's no reason to watch it until you know the original series and understand who these characters are and what the origin changes.
Thunderbolt is a unique style of UC that doesn't connect to other UC media and isn't finished.
Why are you recommending the worst places to start with? Is it because they're short and you haven't watched any of the full series?
Here are the recommended series and why they're recommended.
Mobile Suit Gundam trilogy
The original 1979 TV series was edited into 3 movies with some changes to make it less silly. It's the best way to dip your toe into the water if you are okay with older animation.
Gundam SEED TV Series
SEED was 0079 updated for the 2000s audience. It took the original story's outline and told a more modern story with it. Added more Gundams, more drama and better animation. It's got some issues and it's sequel has a lot of issues so it gets shit on. If you don't mind stock animation being a little over used or you want more of a Romeo and Juliet style conflict between the main characters SEED is a good place to start.
Gundam 00
Before Iron blood orphans 00 was the most recent way to jump into the series. It's animation is flashy and it tells the story of a terrorist group trying to prevent wars by pissing everyone off against them. It has strong characters and Gundams anti-war themes. It's similar to Gundam Wing, which was the intro to Gundam for a lot of the Western fans so they lean towards this as an intro series. It's different to most Gundam but it's a self contained series and movie with Gundams DNA.
Iron blood orphans
A bunch of discarded child soldiers use a Gundam to form a PMC. They go around fucking people up with gritty scenes and lots of bro hugging (No homo does not apply here). If you like edgy gritty slow paced stuff IBO can be enjoyable. It has pacing issues and a bad ending but it got a lot of people on board with Gundam.
Witch From Mercury
You like girl dick.
G Gundam / Build fighters series
If you want a super robot series with Gundam designs this is where you start. The Build fighters stuff is fun and doesn't take it's self too seriously. They are good super robot series and if you want to try Gundam but don't like the war focus these are great.
Anything else is going to have problems recommending because it relies on a previous series (Zeta, CCA, Igloo) or it's an alternative timeline that takes major liberties and makes it confusing to get into the main one (Origin, Thunderbolt, Gquuuuuux). Even the stand alone AU series turn out to be building off of another series (X, Turn-A, Gquuuuux) and they're better watched when you understand the originals.
Gundaminfo has the 0079 movie trilogy up on youtube subbed.
G Gen Eternal, the mobile G Gen game got an update today. It added CCA and Destiny as full series with playable stages. Destiny has 14 stages and you need to beat the G Gen Eternal SEED side story (it's animated and new for the game) to unlock it. CCA is 8 stages and you need to beat ZZ to unlock it. Some of their units aren't implemented yet but all the TV series ones are and the MSV stuff should come soon.
The featured unit for this updates Gacha is Hi Nu with CCA Amuro and Bright and the Ra Calium as a supporter. The Minerva crew and CCA cast make up the rest of the gacha. Only those 2 are FOMOed and have a limited window to get.
