Your best bet, in general, is to get a Nexus-branded device. Those are straight from Google, run vanilla Android, and tend to get updates more quickly. Additionally, they are frequently among the most hacker-friendly Android devices, so custom firmwares and the like from the modding community tend to spring up quickly, so you tend to have lots of options about the software your phone runs as it gets older.

Often times, phones from Samsung or HTC or whatnot come with a customized version of Android, which has been made to look visually distinct, has some additional value-add packages, and whatnot. Most power users will tell you that they prefer vanilla Android. That said, most all the popular devices have aftermarket builds based on vanilla Android (AOSP), or a juiced-up fork of vanilla Android (CyanogenMod, my personal preference), and it's not that difficult to replace your factor-installed firmware with one of these packages if desired.

The S3 is a great device, though, and I don't think you'd regret it if you got it, but if you're looking to get an opinion of Android, a Nexus device is the way to go.

I have a Galaxy Nexus, last year's version of the Nexus 4. One thing I value about it is the Google/non-carrier-controlled experience, which I expect is similar to what you've had with an iPhone. There's not vendor crap on it and it gets updated by Google when there's a new release; apparently Android 4.2 is on the way. Non-Nexus devices have had some difficulty getting updates due to carriers or phone manufacturers.

Updates are nice because they extend the useful life of the phone.

I've never had an Android phone, but from what I understand, the Nexus line are the phones that gets the OS updates when they are released. The other guys have to go through either the carrier or the manufacturer or, sometimes, both before an OS update reaches the phone.

If I were looking to make the switch, it would be this phone.

The S3 and Note 2 have a Samsung-tweaked version of Android. These amount to some different apps, slightly altered UI and in the case of the Note 2 some tweaks to accommodate the stylus.

It's not bad, but most prefer stock Android for the crispness of the UI, lack of bloat and fastest OS upgrades (they come direct from Google without delay while Samsung/another third party adapts their stuff).

I had the Note 2 briefly - it's a powerhouse but ultimately decided it was too big for my taste (5.5" screen vs 4.7" on the S3/Nexus 4). It needs two hands to operate most of the time and the screen is the same resolution as the S3 so you're only gaining in size, not detail. In the end I was happy to come back to my Galaxy Nexus.

The Nexus 4 runs stock Android and is the same size as the S3. It's also cheaper and faster. I'd say it's the clear choice right now.

This is a tough one, and it really depends on what YOU want. What exactly did you like/hate about your iphone? That will help people respond to your question.

I'll tell you what I tell everyone looking for a new phone. Go play with them. Honestly, that is the best way to find the phone that you want considering most of the specs are similar unless you are a power user (ie, flashing new roms, rooting etc). Put the phone in your pocket, sit down, walk around with it etc and make sure it fits your daily life. This is specfically true for the Note 2 which is f'in huge. For me, it's size wasn't a huge deal and I returned my s3 for a note 2 last night. The note 2 is f'in awesome, but it may not be useful to you.

In response: S3: awesome phone, nice features, a few apps you can't delete (I had the AT&T version, YMMV) but overall a very nice feel. I really liked that phone and although it was large (4.7" screen), it was light and easy to use.

Note 2: LARGE. 5.5" screen..which is too big for most people. It also has a stylus (pen) that you can use to write on it and I really like that feature. however, if you have no use for that feature, don't bother.

Nexus 4: I haven't used this yet so I can't say much. what I can say is that it looks pretty bad ass and I'd highly consider it IF it had LTE connectivity. I live in NYC so LTE is all over the place and the difference between that and 3g is pretty significant. This, however, only matters if you have access to LTE networks.

Overall, I think you can't go wrong with any of the choices you are going to make. If you live in the states, and you are on contract, the S3 is going on sale at BestBuy for $50 on Black friday (2 yr contract required). If money is an issue, I'd almost think that is a no brainer.

To be short, just go play with the phone and see which one you like best. Everyone has an opinion, everyone has their own interests in mind, so the only way to really make the right decision is to just interact with the phone yourself. You aren't going to pick the wrong phone, all 3 of the phones you are interested in are pretty damn awesome:)

Oh and lastly, Youtube! Go search on youtube for the 3 phones and watch reviews.

I will say that I just switched from a iPhone 4 to a S3 and it seriously makes the iPhone feel like a toy.

How so?

The size really is a big thing. This phone feels like it's the right size. The iPhone just feels...small.

And then the OS. I didn't like the built-in keyboard, so I downloaded and installed another one. Now "keyboard" is just a preference in the settings menu, and I choose which one I want.

But it's a whole lot of small things like that. Android just feels grown up, to me. iOS feels like a sandbox, like something you'd find in a school or something, or "baby's first telephone".

To me it is because of the sizes. 3.5" vs 4.8" screen is a major difference- the iPhone4 looks made for your 5yr old to play with in comparison.

I think you might want to choose Nexus 4 because it's the cheapest. As I read, they have specs as close to each other. But if you think without having an LTE is a deal breaker, Nexus 4 is not a good phone for you.

question: is the lack of LTE really that big of a deal? how much slower is this other thing nexus 4 uses?

If you will ask me, my answer is no. I'm living in a region / country wherein LTE is still "not there yet". I'm buying this phone because it's cheap. I don't mind the lack of LTE because it's still somewhat useless in my country.

I've found that in areas that have LTE it is a big deal. HSDPA 3G can theoretically get you 21Mbps but I've found this to hardly ever be the case. I have friends that regularly post speedtest screenshots at >35Mbps.

Also the lag on 3G is atrocious. When I'm streaming iTunes Match it's click, wait, start, pause, wait, and then start again. Apparently the ping times are much lower on LTE and this is a bigger deal (for me) than the bandwidth.

I regularly get between 16Mbps and 21Mbps on HSPA+ in my area and the latency doesn't feel particularly different between my LTE devices and my HSPA+ devices. YM, of course, MV.

what area are you in? (if you don't mind me asking)

Eastern Massachusetts, outside of Boston.