"Is it possible to choose which USCIS office processes your spousal visa or to transfer? I've heard testimonies of some offices processing and faster than others."
Unfortunately, no you cannot choose the processing center or USCIS office where your paperwork is sent to. It's going to be sent to one of two lock boxes either in Phoenix, Arizona or Chicago, Illinois. From here, they'll receive your documents and then they use a process which we refer to as "load balancing" to distribute them to various centers. They decide which processing center across the country as the fewest number of cases, or less caseload than the others. And you are right, you can look online at the processing centers to see their current processing times. You can check California, and you can check the Eastern processing center as well as in Missouri, and you'll find they all have different processing times.
Unfortunately, those processing times, aren't always the most current and accurate because they are constantly transferring cases to try to balance work loads out. It's quite possible that your case will be transferred. The good news is as when it gets transferred, usually that means they'll be working on it sooner rather than later. So it's good news when you hear that they've transferred it.