Since Fate/Extra and Fate/Stay night are separate media based on the same universe, there's a high chance that, if you enjoy one of them, you'll enjoy the others. This is slightly less true going from F/SN to F/E and probably more true going from F/E to F/SN. Fate/Zero is the light novel prequel to F/SN, and the anime is based on that. It's still very good, but doubly so when you're already familiar with all the F/SN routes. I doubt you can go from F/E to the F/Z anime and get quite much out of it unless you already like that genre (action/drama), since a lot of the references won't make much sense unless you've played F/SN or you spend a lot of time reading wikis.
If you like fantasy novels, anime, and good stories, you'll be doing yourself a huge favor by playing the Fate/Stay night visual novel. If you like the story and universe in F/E at all, you would also like F/SN.














