which one: xfig, dia or inkscape

[abdelkader belahcene <abelahcene@gmail.com>]

Hi
every body,
until now, I used  xfig to draw   my figures and graphs,  but I am not satisfied, specially when I want to no latin caracters or formula (like in latex)
I tried inkscape it seems better ??? what about  dia ??

I want  to a good choice.
any idea
thanks a lot