So /a/, I saw Rin and I just fell in love. Now I want to watch the anime she's in but it seems there are many Fate anime out there, any guide on how to watch them? Or there's only one I should watch?
There are 3 Fate animes out, and we're getting a movie Soon(TM).
If you want the full backstory to the storyline, watch Fate/ Zero first
If you don't give a fuck about all the backstory and just want Rin goodness, watch Fate/ Unlimited Bladeworks. It's a complete story in its own right and you don't need to watch Zero beforehand, but there are some references you'll have to just roll with.
If you watch both of those and you really want more Fate, then watch Fate/ Stay Night.
So Zero if you want backstory first, then Unlimited Bladeworks. And only watch Stay Night if you really love both of those.
Seriously, you should read the Visual Novel first. It really is the best way. But I understand that it may not appeal to you if you haven't watched the show, so here's my recommended anime-only watch order:
Don't watch Fate/Stay Night (2006). It's pretty awful.
Don't watch the Fate/Stay Night Unlimited Blade Works movie (2010). It's pretty awful too.
Watch the first season of Fate/Stay Night Unlimited Blade Works series (2014).
Watch all of Fate/Zero (2011).
Watch the second season of the Unlimited Blade Works series.
Unlimited Blade Works makes several references to Fate/Zero, particularly in the second season. However, Fate/Zero is an awful introduction to the story.
If you want to animeonly - new UBW & HF and then F/Z.
VN then either Fate route -> UBW route / UBW new anime -> HF route / wait for HF movie -> F/Zero
Watching Zero spoils everything else
unlimited blade works
the tv show, not the movie
don't listen to these retards, the vn is long and tedious
Best version of the story is the Fate/Stay Night visual novel. It's really long though.
If you can't into VNs then the Ufotable anime adaptations of F/SN's Unlimited Blade Works route and Fate/Zero are your best bet. Then maybe Prisma Illya's manga/anime. The first two series have quite a bit of Rin.
If you are into VNs then read F/SN followed by Fate/Hollow Ataraxia.
Start with the Unlimited Blade Works movie drinking game.
You get some friends together and watch the UBW movie. Then you ask each other what happened in it and why. Then you drink to dull the pain.