A lot of people have been angsting over Apple's move towards a closed development model, where only software approved by Apple can be run on your computers. And I am too. Especially given some evidence that non-approved software is actually safer than Apple-approved software.
But I'm even more worried about their move towards the system they have on iOS where all programs are locked into their own little sandbox and can't even see information owned by other programs. Not to mention that they're pushing more strongly for all your data to be "in the cloud", under Apple's control rather than yours.
I've been a Mac user for a long time but I'm predicting that sometime in the next five years I'm going to have to jump ship. The water's not boiling yet but I can feel it getting warmer.
GNU/Linux is always there for you.
I've been a Unix user for even longer than I've been a Mac user, so I hope the learning curve won't be too steep, but yes, I suspect learning more about Linux is in my future.
Android is up and coming but it has many of the same lockdown issues as iOS, so I'm not hopeful of an escape in that direction.
I have been using Ubuntu for years now and have been happy with it for the most time. What you don't like you tinker away; that's the power of GNU/Linux. Also, there are myriads of distributions to choose from.
Nowadays, if you install one of the more mature distributions, you will probably have at least the comfort of proprietary OSs. User interfaces have become very good, without taking the power away from you.
I share your sentiments about Android. If I wanted to have a smartphone I am not sure what I would do. I am sure there will be some that run a proper, i.e. open, Unix some day.
there are some open-source Android projects, e.g. http://www.cyanogenmod.com/
I'm very tempted to jailbreak my Android cellphone, but unfortunately cyanogenmod doesn't work for it (it's a Droid 2 Global — cyanogenmod supports the Droid 2 but not the global).
Apple has been going the way of "protecting users by reducing choice" for quite a while now. Sandboxing and the closed development model is just the most recent of them. Before that there was their arbitrary (and occasionally anti-competitive) app approval practice on iOS. Go farther back and you have them filing patents by using 3rd party app screenshots as an example of what their patent covers. Or heck, patenting pinch to zoom (which had full prior art in papers prior to 2000, and was in videos about Microsoft's interactive table around the same time), and their entire "sue everyone" strategy based on software and borrowed/stolen UI interactions. I could go on, but it's late, and my hate is waning.
Apple has never been about being legitimately open. But they've done a pretty decent job pretending that they were.
In terms of switching, there's FreeBSD and a whole gaggle of Debian-derived distributions. Both are solid and have enough users to get a critical mass of forum posts to fix almost any issue you are having. Recent Ubuntus have moved to a Unity, but you can replace it with KDE, Gnome, or whatever you prefer.