So I recently played Broken Sword 1 Directors Cut on my iPhone.
It was an ok game, but definitely not my favorite P&C. I don't know, I found that Stobbart guy a bit bland and missing some backbone.
(I also found it annoying how Stobbart went to Spain, to visit the Vasconcellos, and even though they were in Spain and the family name is clearly spanish, they pronounced it like it was italian, but I am digressing.)
Still it was good enough that I am willing to continue with the sequels. I don't know anything about Gabriel Knight.

Anyway, what do you recomend for my next P&C?
BS2 Or GK1
How do they compare, what are the strengths and weaknesses of each one, what's the better story, etc.

I can only really speak to Broken Sword 2 as I have only played a little of GN1 and got quite bored.

BS series is one of my favorite games, I loved the characters and storyline, as such this is a continuation of a tightly nit storyline. I would like to think it ends quite well at BS2 because BS3 and 4 aren't quite your traditional P&C.

I highly recommend that you play BS2 next, it is a fantastic game.

EDIT: I'm interested to hear that you played BS1 on your Iphone (finally a reason to buy one), I hope the intended atmosphere was represented on a mobile device as it stands on the PC version.

Yes, I think I will play BS2 next. Over at the GB forum they seem to agree too.

On behalf of the intended atmosphere. I didn't play the original BS in its time, so I can't really comment on that. It was definitely not one of my favorite Adventures, but that wasn't due to the atmosphere, the atmosphere was really good, but I found the main character a bit bland.

I can comment on other games tough, I played "Beneath a Steel Sky" for the iPhone, and honestly, I liked it A LOT more on the iPhone than the original.

I also played Simon the sorcerer 1 and 2, The Secret of Monkey Island Special Edition, Flight of the Amazon Queen and Myst on the iPhone, those where essentially ports of the PC version, some better done than the others, but they didn't differ much from it's original PC counterpart. I've also played a lot of classic games that aren't adventures, but the best part is they are dirt cheap.

I haven't played Gabriel Knight yet, though I am planning to, but I can recommend Broken Sword 2. It's a very good game. Too bad it all went downhill after that. I have played the original version many times, and recently purchased the iPhone version. It's an amazing port. The extra puzzles are so-so, but the additional story-line about Nico was very nice.

I like Broken Sword games, but Gabriel Knights are definetly much better games. The stories alone is superior to Broken Sword, especially in GK1 and GK2. The Third one isn't bad either.

I'll second the rec for GK. Simply one of the best adventure series EVAR! The GK games are not without flaw, however. The biggest is Tim Curry's absolutely horrid New Orleans accent in GK1 and GK3. I really don't know what they were thinking here. To take an actor of that caliber, and force him to do an accent he is incapable of pulling off borders on criminal. They cold have easily tweaked the story to explain his English accent.

However, if you can ignore that one jarring note, you'll find some of the smartest writing and engaging plots you've ever seen in an adventure game.

My personal recommendation is for Broken Sword. I didn't find Stobbart bland at all - I thought his ironic angle on everything makes him a pleasant and amusing 'everyman' character.

Yeah I didn't find Stobbart bland at all. But I guess since we don't really learn much about him, or what his life was like before he suddenly turned into an international history detective, can be off putting.

The way he carries around the hand buzzer, and keeps asking what people think of the disgusting tissue, make me laugh every time.

GK series is awesome too, and there is a bit of overlap with the subject matter (historical myth shakeups etc). I couldn't pick a favorite, as far as story goes. For gameplay I prefer BS, puzzles in GK get a bit on the annoying side at times.