First of all, I would like to say that the computerized boards being demonized in Japanese cars are present in all new cars, including Cultus, so that's not an issue. What is an issue, is the after sales services and engine capacity.
The 660cc JDM cars are good enough for city, but as soon as you start using them for highway travel, they will start giving problems. Their engines are not made for highways. So I would not recommend that. The problem with 1000cc JDM cars is only of spare parts and after sales services. However, I have seen that Toyota and Honda dealers provide support for their Japanese cars here in Pakistan. So, if you buy a Vitz, you can get it's services from authorized Toyota dealer. Though they are expensive, but so will be the Suzuki authorized dealers in case of Cultus.
Overall, in my opinion, Vitz is a better car as compared to Cultus, and if you can afford, and have the space to park Aqua, that would be the best. I feel that the Cultus VXL is quite overpriced. Apart from the price, it is a decent enough car though. Vitz is so much in the local market that it's parts are being made by local parts manufacturers and it's support is available, just like a local car. I would rate Vitz above the Cultus in comfort and reliability.
As for FAW V2, I would recommend it if you want to spend lesser amount of money and get a good package overall. But if you can afford a Vitz, I would recommend buying a Vitz over a V2 and a Cultus. But that is my opinion, you might agree or disagree. What you can do further is to go and take a test drive of all these vehicles, and compare the specs sheet. Go with whatever car you like after seeing it yourself. We can only give you different points about cars. The decision has to be taken by you.