I've had a second gen iPhone for 4 years and my new Atrix HD will arrive from Amazon tomorrow. I've been researching the switch for months and after playing with the Samsung, HTC and Nokia phones, the Atrix HD is a breath of fresh air. For me, NFC is more of a bell and whistle then something that adds important functionality, but you may view it differently.
The closest comparison to the MAHD is the HTC One X in my opinion. And after monitoring the One X forum for a couple of months, it became clear that the hardware has problems and the Sense UI removes a lot of the important functions of vanilla Android. In comparison, the Moto UI is nearly stock Andriod, the screen is easily as nice or nicer than the HTC, the processors are identical as is the RAM, and it has a microSD slot, which some claim will handle a 64 gb card. Even if it only handles a 32gb card, that still makes the total storage nearly 40 gb, which for me is way more than enough.
I got mine at Amazon for $50, no tax, shipping or restocking fee and I can't wait to get it. If you're not with ATT already, you may not want to get it at Amazon though since they have an additional ETF on top of the one ATT has if you cancel your contract. I like ATT so it's a no brainer. I just saved nearly $100 which is huge in comparison to the cost of the One X or GS3, which to me, don't compare.
Whatever you decide make sure to use this community for help. The people here are awesome which makes the transition fro iOS to Android so much easier.