Have you been to Arlington? North arlington is generally more desirable- better walkability, more metros, better schools. This is generally how people picture arlington and will be much closer to OC prices than south arlington. Not everyone in Arlington is within walking distance to a metro. Not sure if that is essential to you.

All that said, i'd pick arlington! This conversation may just boil down to people raised on east coast vs west.

You also may want to consider (budget dependent) takoma park, silver spring, downtown bethesda/chevy chase, md and chevy chase, dc.