A couple of thoughts. First, if this is a one time project, don't buy a cheap nail gun. Go to a professional construction distributor and rent a professional quality machine. It will make a huge difference.
Second, as was mentioned earlier, you will need to consider the materials you're using when selecting the right nail. A professional fastener distributor will be able to match you up with the right product. The last thing you need is a nail or coating that has an adverse chemical reaction with your building materials.
Third, don't worry about coatings on the nail. They don't really do anything. There is a case to be made for vinyl coated 16d sinker nails, but those are hand driven. The reason for the coating is that the vinyl melts under the friction of the hammer blow and makes the nail sink faster and easier. That isn't an issue with a nail gun. They will try to tell you that coatings make the nail stick more firmly once it's in, but that's just a myth. The nail isn't going anywhere regardless of the coating.
Fourth, there are specific nails for specific applications. Calling a manufacturer and getting the perfect nail for the application can be a life saver. One of the best nail manufacturers is Tree Island Industries. They have an excellent customer service department. Ask them for their catalog and ask their rep which nail to use. Here's a link to their site.
Customer Service | Tree Island Steel
Finally, for generic framing, it doesn't matter what type of head you use. The nail is in once it's in. If it's going to pop it will do it one way if it has a head or the other way if it doesn't. The nail gets its strength from the length that is driven into the wood. Friction keeps it in. That's why sinker nails are the specific dimensions they are - they're the perfect length to fasten two 2x4s together without sticking out the other end and without splitting the wood. The nail gun equivalent is the 151 nail which is actually a tiny bit smaller than the 16d but it doesn't matter. The size of the nail you need depends on the framing you're fastening and how thick the pieces are.