watch them in this order. The first 3 are on Netflix, i'm not sure where you can watch Gundam ZZ and if you have a VPN or are in Japan (or buy crunchyroll premium), you can watch Gundam Zeta on Netflix. after you watch those then you can look into the spinoffs like Iron-Blooded Orphans, The Witch from Mercury, Gundam Wing, and all the others
P.S. also if you want some more Char Aznable watch "Mobile Suit Gundam: Origins" it's very good
