I figure this would be the best place to ask. I'm looking to start a WH40K book collection. Any top 3 Iron Hands readery to be suggested or should I simply start from the beginning?

Imo its best to read from the begining all the books so that you have a better understanding!

If we're speaking about the Iron Hands, then Wrath of Iron is sadly the only good option for an actual full novel in M41, and that's notably flawed. Definitely good, but flawed.

Otherwise, if you are starting a collection, i'd personally have to agree with Galen that the beginning is your best bet. Not the Horus Heresy itself, but a longer standing series like Gaunt's Ghosts, the Eisenhorn trilogy or Storm of Iron and the first Ultramarines omnibus. That should give you a good, broad depiction of the setting I hope. From there on it would be your own choice of course, but if you were looking into Chaos i'd personally suggest the Word Bearers omnibus to start with, and perhaps Path of the Dark Eldar as a xenos option. Well, that or Fire Warrior if you can find a damn copy of that book. This is just personal opinion of course, but they seem to be the best entry points into the setting as a whole.

The hands were corrected after the image was released.

Dat left guy. He's like "I haz combi-heavybolter". Seriously, that heavy bolter looks like an underbarrel attachment for a bolter. It's awesome.

That's based on the Forge World legion heavy bolters, which were made so they could be used with bolter arms, the lazy bums.

I know. Makes me wonder how would it feel to fire that thing.