I like
Alec very much as a stand-alone name. As a nn for
Alexander, I don't think it would work: there are so many
Alex people that it would just morph into
Alex however hard its owner or his parents tried.
Not another two-syllable name, I don't think; not a short a sound in an accented syllable either. So:
Alec John;
Alec James;
Alec Paul;
Alec GeorgeAlec David;
Alec Peter;
Alec Gareth, though the -c and the G- are a bit odd together;
Alec Edward;
Alec Thomas;
Alec LeonardAlec Benjamin;
Alec Nicholas;
Alec Sebastian;
Alec William