Ok, so you definitely sound like you should go Android (“Lots of things to experiment with (I love experimenting with technology)...”). You’ll love being able to make your phone do anything you want.
That said, the variables you should probably consider are…
– removable battery
– sd card
– vanilla, stock Android (Nexus) or some other flavor (Samsung’s touchwiz, HTC’s sense, etc).
– screen size
– stylus/no stylus
– hardware button(s) or not
– carrier restrictions (not all phones are available on all carriers)
So, when you are researching and considering these things, you will want to see how important they are. For example, going with the Nexus 5 will give you the pure Google experience (KitKat, Android 4.4) and will guarantee that you’ll get updated right away when the next version arrives. Samsung and other hardware manufacturers modify Android to give their phone some proprietary nature and to stand out. But the consensus is that you never actually gain anything. It’s not good. The plain, vanilla Android experience is always best in my opinion.
But then there is the question of sd card and removable battery. I love having a removable battery because we will lose power here and I will travel/camp, and I love the ability to just drop in a new battery whenever I’m low. As for the sd card – I bought a 16GB phone and for $12 I bought a 32GB sd card and loaded it up with music. But for some people, it doesn’t really matter. They use Spotify or some streaming service and they don’t really want a ton of storage.
Screen size is a personal preference. I have a Samsung Galaxy Note 2 and love the size (5.5 inches). But the good thing about Android phones is that you have many options. I haven’t heard the rumored S5 size, but the Nexus 5 is 5 inches.
Stylus is a less-common concern, but I thought I’d mention it. The damn Samsung Note series (which I have) has a stylus. You can write hand-written notes all day, it’s extremely accurate and has a very fine point (it’s not like a tablet think stylus, it’s like a very sharp pencil). I didn’t want a stylus, but I have it and hardly use it. I got the phone for other reasons. Just happened to come with the stylus. Some people (artists, etc) really like it.
Then there is the hardware button(s). Again, I bought the Note 2 for other reasons, but I’m having to live with the physical iPhone-style home button that drives me crazy. My recommendation is to go straight virtual (or at least those soft buttons on some phones). Android’s back button is essential and really sets it apart from other platforms. You might also consider the placement of that button (virtual or not) – you’ll be using it all the time.
And then there are the carrier issues. Since the Nexus 5, for example, isn’t available to be activated on Verizon, you might be limited to the phone if you need to stay with a particular carrier.
Then there are other considerations, such as Motorola X’s “always on” functionality, which allows you to interact with it while it is “off”.
Good luck with the decision, and feel free to pm me if you have any specific questions. Also, you might want to also google “Tasker” if you want to drool over what you can do with whatever Android phone you end up with.