Any comparison as the DHA distance is almost 16 km ahead from Bahria Town.
Bahria Town will never sound as chic and classic as Defence. Baaqi i think living in Bahria Town may sound a better option for many primarily because of its covered premises and monitored entry and exit points.
About investment, the better option is always the one which offers sound ROI and in that case, BT is should be your pick since value of property in Bahria Town starts on small and multiplies many times with development.