I started in 2005. Quit and gave account away during the pre-BC patch. I started again in WotLK and imo, as far as expansions go, that was a decent expansion(and because of muh lore). However, I don't think I've never been a fan of pumping out new content and outdating the old, starting with TBC. 60 as level cap forever would have been fine.
Granted, if they bump out an expansion that provides as much gameplay and content as Vanilla did, then good for them, but I don't really see that happening, as most of their interests seem to revolve around money and not setting us out on epic, immersive adventures.
I played a bit in Cata but that was because of scroll of res + the twink battleground exploit that allowed me to queue twinks into non-exp locked battlegrounds. It was fun for a while, but in Cata already you could see they were running out of ideas and just repeating the same formula over and over again.
I did pop out every now and then on PTR(in fact I built a machine and bought ram specifically with multiboxing on the PTR in mind, since it's free) in Cata and MoP, and recently even in WoD before they disabled the auth, but for me the experience in WoW, especially the experience of an epic world to explore, has become progressively worse. It has come to the point where I no longer concider WoW as something that is targeted for me. Even though I could play for free on the PTR, I was never really amazed by their design choises or "core philosophies." The way they cling to raiding as the end of all means for everything, is also troubling, given how little % of their playerbase has statistically and historically enjoyed it. Given their inability for branching out, as well as the new facebook-y minigames, wich further serve to only destroy the immersion in WoW, I see very little point to subscribe, let alone buy an expansion set, in the future. They need to get back to their roots, but it won't happen, because of money, and LFG/LFR are already too integrated to the game and the casual audience to be taken away. Even if I would not have had access to PTR, I would not have subscribed.
As such, the only logical course of action any smart man who values different things than the current lead devs do, is to unsubscribe and just not play at all. I do not wish to support the constant invalidation and dumbing down of content in WoW - I desire a more hardcore experience where WoW feels like WoW. Unfortunately, I see that only possible in Vanilla and hope these servers will only get better over time.