It's basically "DHA" vs "Bahria" at this point in Karachi. People generally consider both societies as equivalent, but there is a huge difference between both. Lets differentiate:
DHA:
DHA is Army/Government operated. Unlike Bahria, it's less influenced by politics and big dealers/brokers. Politicians have to be in good terms with Army while Bahria has to be on good terms with politicians, to smoothly carry on their businesses. Creation of Altaf Hussain university is sequel to the same.
Due to its enormous muscle and financial power, the Army operated DHA purchases and develops huge amounts of lands. It can literally develop an entire city out of it. Success of DHA lies in its foresightedness. DHA commenced in the 1970's while Bahria started somewhat in the 90s. The land which DHA acquired in Lahore in the 70's is now the centre of Modern Lahore. Anyone who has visited this city might be well acquainted. Same goes for Rawalpindi/Islamabad and Karachi. DHA began its operations here in the 80s on barren lands but have shifted the momentum of these cities towards itself.
Bahria:
Unlike DHA, Bahria is a much smaller society. It's considered Asia's biggest as it's privately owned. It keeps on struggling with issues like land acquisition. People had been victims to its land grabbing issues, land mafia etc. It has to face courts for the same reasons as well. Now where lies its success ?
Bahria believes in quality than quantity. It's far ahead of DHA in development, landscaping, marketing itself with projects like Grand 7th largest Mosque, World's 3rd largest mosque, creating replicas of wonders of world etc, powering itself with own grid stations, creating a gated community etc.
It's success lies with being close to DHA. One such example is Rwp where it was a huge seccess. When it deviated away from DHA like in Lahore or Bahria enclave, it has somewhat suffered with small investors facing the brunt of it. Bahria Rwp phase 1-7 are the perfect examples where it has outperformed DHA. Bahria Lahore, Bahria enclave would have been much much more successful, had they been located with DHA. People prefer living in DHA Lahore than Bahria, as the former is city's present and future centre (Due to Airport and commercial centres)
DHA City vs Bahria Karachi:
Situation for DHA and Bahria is the same as it was in Rwp a couple of decades ago. Now Karachi posh areas are over-crowded. It needed a new direction to expand. DHA being one of the biggest entity in real estate took initiative and lead the way towards super highway, the same way it did in Rwp by moving along GT road. Bahira followed and located itself adjacent to DHA City karachi, which is very wise decision. This area will be the downtown of modern Karachi, considering proximity of Airport, Malir Cantt and M9 Super highway. So long term investment here i.e 7+ years is very wise and profitable.
Due to the hype of Bahria, it undergoes two Phases:
Phase I: Plots on ground aren't alloted and files are dealt with. It's more like a Bahria stock exchange at this stage. Major investors and big guns hold maximum files and thus regulating the prices. These dealers mostly focus on short term investments and files are traded a lot in market. All people who buy at this stage actually don't plan to live or construct houses on these plots. It's only aimed at financial gains.
Phase II: After about 5 yrs, BTK maximum files will change hands and reach middle class and small investors who want to use land for their living. Prices get stabilized at this point of time. People commence constructing their houses. So for long term investment, it's a much better option. Bahria enjoys superior location than DHA city in Karachi. It will just take time for files to reach the actual residents.
Secondly, Karachites have seen DHA a lot but have never experienced Bahria town's living, altough they've heard a lot of praises. So obviously a lot would like to experience it.
Thirdly, people want security in Karachi. BTK will serve as first GATED high class community and a secure environment. Elite class and overseas Pakistani will surely prefer it.
Fourth, this city is full of elites who can afford to keep more than one house. Most of them own one in DHA and won't mind buying another in Bahria
Fifth.
Lastly, Karachi is larger than Lahore and Rwp/Isb combined and has got a huge population. Icons like 3rd largest mosque, international theme part etc will attract the masses towards it.
So my opinion: Bahria town Karachi is much better option.