A question I've been increasingly asked is, "Which phone should I get my ____ for their 1st smartphone?". Subtracting any strong allegiance to a specific OS, I've been recommending the Nokia Lumia 900 over confusing Android devices or expensive iPhones for casual users (hardcore users, note I used "casual", aka not you) for a variety of reasons related to everyday comfort/utility...
Despite its "flagship" moniker, the Lumia 900 isn't cutting edge in features or specs (ahem, Nokia, please upgrade that camera already). But, the 900's unibody construction is rugged and provides an assured grip, it takes advantage of LTE network speeds, the screen offers a satisfyingly rich-dark contrast pop, and the design itself is attractive enough to garner curiosity amongst the iPhone set (although friends keep mistaking mine for an iPhone in a cyan case).

After months now of wading waist-deep with Gingerbread/Ice Cream Sandwich powered Android devices, I'm left with a bit of a toothache, and I still believe the Windows Phone's user interface is the most elegant of the trio of players right now for "get things done" utility. Power users will still love Android, aesthetes with the bank account will drift to the iPhone, but I'd argue the Windows Phone Lumia 900 coud be seen as the handset for everyone else.
Note: the Lumia 900 is about to receive a pair of upgrades to "Windows Phone 7.5 Refresh", then a "7.8 upgrade" which will align the 900 with the next generation of Windows Phone 8 devices, providing many of the UX bells and whistles promised by the upcoming operating system upgrade. For many 1st time casual users, this won't matter all too much when the user is just seeking a fun phone to use without hassle, worry. And it's for these simple reasons the Lumia 900 might be the perfect starter smartphone.
Available for just a penny via Amazon, if your mom, dad, young sibling or any 1st time smartphone device user is looking for something that "just works", and has little concern about keeping up with the Tech Joneses, the Lumia 900 is an easy pick.


Sprout Side Table
I would second this with the caveat that this phone isn't going to be upgraded to windows phone 8. Still, I've used this phone and android, and iphone. This is pretty much the easiest to setup without any hand holding.
I would also say that if someone has had an ipod for years and used it heavily (music and podcasts and such) and is thus very familiar with the itunes software on the desktop, an iphone could be an alternative. But I wouldn't wish the desktop itunes software on my worst enemy.
Who'd want a smartphone with a tiny software library that can't be upgraded to the next version of its OS, which is due to be released in weeks? Seems like a waste of time, regardless of the price (there's a reason why they're givin' 'em away).
I'd rather have an older iPhone, like a 3GS. But if you absolutely, positively don't want an iPhone, Android is the only viable alternative.
(I also find Windows' ridiculous tile-based, slide 'n flip interface to be incredibly difficult to navigate. I can't imagine newbies would find it easy. I think they'd be instantly lost.)
I,d recommend the Nokia N9 if the person can afford it ! If they can't I'd recommend the Nokia 700 or 701 , failing that the Lumia 900 ...
For those that caution against the Lumia 900 because it won't get upgraded to Windows Phone 8 I encourage you to read more. First off, they didn't even announce ANY of the consumer features yet. Second, this is the exact same scenario when updating older iPhones, Apple just chose to lie to you and gloss over all the features that the older models will not be getting. Don't even get me started with Android upgrade paths... they really don't exist at all.
My gf just switched from an iPhone 4 to a Lumia 900 (while even breaking contract) and couldn't be happier. She loves the Lumia styling and Windows Phone 7. She was an early adopter of the iPhone and switched to AT&T the very first day it came out, so making the switch was quite a big move for her.
Sure iPhone and Android still have their user base but that is quickly shrinking, especially when Windows Phone 8 comes out.
Lumia 900 is a great phone and all 3 of my close friends/family that have one absolutely love it. I would still recommend it to anyone... Have extra cash and have an eye for aesthetes: get a set of matching wireless Nokia Play 360 speakers with your Lumia. Want the fastest phone around: don't look to Android, Windows Phone runs circles around all of them in most cases (it was the first to use graphics acceleration across the entire OS). Are you a power user: stop flashing different roms that you don't even write and start developing software. Windows Phone has easily the best developer software.
Sorry for the rant; I'm just tired of the user groups frequently assigned to these 3 mobile ecosystems.
Did you recommend the Palm Pre back in the day?
As an iPhone to Windows Phone convert I second this recommendation. True, WP "only" has 100,000 apps but they are high-quality easy to use apps. Plus, the integration of the social networks into the phone itself (no app required) is a huge benefit. Check out #smokedbywindowsphone on twitter to see what I mean.
I've used lots of phones and WP is by far the easiest and most pleasing phone to look at it. Android is by far the most cluttered. iOS used to be the easiest. The "live tiles" in WP are a unqiue feature too. Unlike app icons, these tiles are "live" meaning they give you info without even opening the app. The USA Today app is perfect example. The tile updates several times throughout the day with photos from the top stories -- but this tile is two sided so it will flip over and show you the weather in your area. It does all this without even touching the app! So unique and under appreciated.
True, my phone won't get the WP8 upgrade but that doesn't mean it won't get upgrades. I have 12 months left on this phone and I know I will get most of the wp8 features in wp7.8. Frankly, I don't know why someone is making a big deal about this anyway. Who keeps their phones longer than 18 months anyway? My iPad 1 doesn't get all the cool new features like Siri - I don't hear anyone complaining about this. (BTW, I'll by upgrading my ipad to a Win8 tabet this year)
If you're worried about not getting WP8, then just wait until Fall and get a WP8 phone. The new hardware will be better anyway.