I haven't played OOS, FS, or FSA. I'm halfway through Spirit Tracks, two thirds of the way through OOA, and almost done with MC (what's sad is that I got MC a week ago and the other two months/years ago). To be fair though, OOA is only taking so long because A. it's hard and B. I got frustrated playing it on the Gameboy Player for the Gamecube because the game would freeze up and I'd lose unsaved progress. Spirit Tracks is just a struggle for me because I don't like the train very much. So far it's the only Zelda game that really has more moments that feel like a chore than fun moments for me.
I'm thinking that by this time next year I could play all the games in the series. I got the FS anniversary edition on my 3ds, I've seen FSA on sale used for $18, and OOS will be the hardest to locate but if I'm down to one game left to complete the series I'll pay a decent amount for it online. Soon my problem won't be having played all the games in the series but rather having finished them all since I already currently am backlogged. In addition to the games I've mentioned already, I have playthroughs in progress in LoZ, ALTTP, LA, OOT, MM, TP, and SS. Why can't I just play a game straight through and not stop at random points. This is going to take forever.