Just ignore 'em.

I'm lucky enough to only have run into a select few dickheads in my time playing FFXIV.
There's only been a handful of times when people have called me out on my gear (apparently full Darklight and an i70 weapon isn't adequate for AK according to some people)

Ignore them. These people are generally the immature douchebag type who are only there to illicit a reaction from you
They are like crying children who are begging for a new toy. Ignore them long enough and they eventually go back to sucking their thumbs.

Like others have said, I recommend finding a friendly FC to take you in.
I haven't found the right FC for me, but I'm sure you can find a good one.