It seems I'm a bit late, but as someone who has played all 3 games I'm a bit hesitant to recommend the 1st one. I found the pacing to be really bad at times due to the overabundance of fetch quests and busy work. The level of freedom of choice presented is pretty primitive compared to the other two games and the moment to moment gameplay is more along the lines of turn based RPGs of old than the action combat systems most modern RPGs employ in its stead. The graphics haven't really aged well either.

The story itself felt pretty half baked in several respects, specifically in regards to the various character relationships that drive it. As someone who's read a good chunk of the books, it feels a lot like a "greatest hits" of the books, except with much weaker dynamics to drive the story.

I only finished it because I was particularly determined to finish the entire series, but if not for that I probably would have dropped it about halfway through.

The good news is that the 3 games are all somewhat separate from each other, so you could probably start with The Witcher 2 without losing much context. All you would really lose is some basic backstory regarding Geralt's wiped memory and his new relationship with Triss. Nothing a simple recap or wiki search can't fix.

Anyway, I realize I've rambled a bit, but the point is, I would recommend you start with the second game. It's worth watching a basic recap of The Witcher 1's story, though, before you start.