Gods, I could go on and on and on about Gundam but I'll try to keep it reined in.
If you're trying to get into later Gundam series, then I would recommend Wing first because even though the whole warriors vs. pacifists does get old as hell, it does work very well with trying to do a retelling of Gundam 0079 up through the end of Zeta Gundam.
Zeta Gundam will definately make you go nuts in the latter end with "Ol-Kill-em-All" Tomino hitting some good form here.
G Gundam is great if you're really into Sentai or Giant Robot shows like those that frequent these boards, and which is why it's probably so highly regarded in here and sort of shat on in many other Gundam forums or whatnot.
Seed was pretty good, especially in comparison with Destiny. However the fact of the rewrites they did to Seed after airing it all & working on Destiny to make it fit with Destiny instead of the other way around still gets in my craw. I'm sorry, but HE should be dead. If you don't know whom I'm talking about, you will if you look around for Seed & Destiny.
In the end though, I'd say get any Gundam Series you can and enjoy. They all have their own little quirks (and I STILL think Gundam X gets no love) but honestly, any way you try to get into it you'll have 30+ years of catch-up watching to do.
Now if you'll excuse me I have to assail my eyes and brain by watching ZZ Gundam.