You definitely want to talk to an attorney (I'm not one). But here are my thoughts.
My answer is based on the assumption that you don't have any actual legal entities yet and that when you say "co-founder" you mean a "co-creator" of each of the apps. And that by "own more than 70%" you mean that you contributed more than 70% of the effort to create the application.
The first thing you need to figure out is what is your goal. If you are just trying to create a legal entity to wrap around your products and the ownership, then a single company is probably sufficient if you can figure out a way to fairly value the input that all of your co-creators have put in.
There may be legal obligations in terms of ownership you have to each of these co-creators as well. Do you have any legal agreements with them at all? Did you pay any of them for any of the work they did? Definitely find an attorney who specializes in business law and walk through this part of the issue. It will cost you a little bit of money, but it's well worth it to make sure you do things right up front.
If you want to start generating revenue or getting investment to create a business from these applications, then you may want to consider different companies based on the market space that each app (or group of apps) addresses. This might make it easier and cleaner to get funding for one particular application (or small group of apps) without "muddying the waters".
In other words, say that you have app A that is doing well, but app B is in a different market or isn't doing so well. If you want to get investment to pursue the business of app A, how will you justify the value of app B to your investors? Your investors may also want to ensure that their money is ONLY invested in app A. In this case, it's to your benefit to have separate companies.
I'm curious what you will end up doing. Let me know.