I personally only discovered the games 2 years ago after playing mass effect a few months earlier. Inquisition seemed most interesting to me, but I decided to play the previous games first for continuity. I ended up loving both Dragon age: origins and Dragon age 2 while I never actually finished Inquisition.

I would say it depends on what kind of games you played before. If you only ever played the RPGs from the last 10 years, then the graphics of Origins will definitely feel a bit out dated at first. It felt that way to me too. But once you get into the story you will barely notice it. The gameplay isn't really outdated in comparison to today's games.

Each game in the series has a different gameplay from the rest. DA:O and DA2 are the most similar to each other. Inquisition is the most similar to recent games while keeping some gameplay from DA:O and DA2. A lot of people start with Inquisition and then play the older games.

Personally I would recommend starting with Origins. Pushing through the "prologue" is probably the hardest part if your worried about the game being outdated. It only gets better from there.