Well, I like the name
Alexa. I think it holds all the substance of
Alexandra but is less of a mouthful. I don't consider it to be trendy.
Lexi is definitely trendy, but
Alexa has the same feeling as
Alex for me. Apparently, it is fairly popular, but personally, I've only ever known one
Alexa. I knew one
Alexandra in high school, an
Alexander from kindergarten, and one
Alexandria from soccer.
I think nicknames are avoidable with
Alexa. It's short enough. I have a (female) cousin named
Alex (just
Alex), and her name never gets shortened. That's why her parents named her
Alex and not
Alexandra; they hate nicknames.
My favourite
Alex name would probably be
Alexandre. I also like
Alexis (for a boy) and
Alexandrine. My favourite nn would definitely be
Sacha.
Sandra and
Sandy are both cute names too though.