Hi, if I had to pick between the two makers, it would have to be Arrieta. I've owned several different models of the AyA line, but IMO, Arrieta has the edge on overall care that went into the the making of the gun. This is based on comparing like quality models, say an Arrieta 557 to a AyA Number 2 for example. Of course there may be a difference from gun to gun, I'm just talking in general. I would not count out the offerings by Grulla or Garbi.
Best thing to do is look at each in person and see what one tickles your fancy.
Good Luck!!!
Greg
