Are you talking about the charging station, or a permanent spot for the laptop?
My last agency had the charging station in the back, which really sucked. Sure, I could do the PCR on it in the back, but often times I'd be up front to finish it, and it wouldnt be charging, and at the end of the call is when you're most likely to have a low battery.
At my new agency, the laptop is on a swivel charger in the front, because not only are the PCRs on it, but so is the CAD and navigation software. Going to calls, use it to navigate. Once on scene, disconnect it and it foes with the medic in the back of the truck. Done with the call, and it goes back on the charger on the front.
As long as the laptop is mobile, front is best.