Start them all from 1st to last
If you do, you'll have a blast
Origins is the 1st to try
Though old of graphics
The cake isn't a lie
Next delve into DA2
I really like like it
Some think it's poo
Inquisition is next on the list
Some find it confusing
But some get the gist
All in all time and money well spent
People that don't like it? Ya'll can get bent.
This is genius.

I'm just gonna echo a lot of others but hey, why not.
I'm still playing Inquisition, but having done them in order I would definitely recommend doing so, as the story carries through and it makes much more sense if you do. If nothing else, you should play Origins first before Inquisition.
Of the 3, you *could* get away without playing DAII, as it's probably the most encapsulated of them all, HOWEVER - you will need to catch up with the story and characters otherwise some bits of Inquisition will have have you scratching your head as they won't make sense.
A lot of people will tell you DAII is rubbish - a conclusion that I fundamentally disagree with; but you should make your own mind up. It's Very Different from the other 2, almost like a Visual Novel in parts - (not a bad thing) - and somewhat the result of "Pressure to Publish A Follow Up" - which is a great shame because actually it's a really good-looking game with a great story and characters, and decent gameplay. It's just let down by feeling a bit rushed in some aspects. Bioware wanted to try something different and they were, in my view, very close to pulling it off.
I thought it had a great, slightly melancholy feel to it as well - (although the same could be said for every game in the series, in fairness).
Anyway: play them in order, that's the best bet for the full experience. 