For the DLC, I'd have to go with the PXH. It's also what I'd personally prefer to run on the tabletop. The unit's mission profile calls for speed, and the PXH delivers. While the thinner head armor on a PXH seems scary, it's normal role would see less inbound fire than the other options, and most of what it does draw would be against scouts without enough firepower to head-cap a 'Mech anyway. The prestige for running a shiny new 'Mech with all of the latest bells and whistles is also good for one's image. Normally, a PXH is a lance-leader for a Recon unit, which after an initial training period under a veteran lance leader would allow some flexibility and experience at command. The Enforcer means you'll most likely be a cog in someone else's wheel.
In other situations, I'd be torn between it and the ARC. With only half the DHS functioning at full efficiency, it's still quite capable of delivering its full missile payload without overheating. Basically, the "problem" isn't a problem, and the heavier armor and usual supporting role means a greater chance of surviving any engagements, although there's significantly less prestige in that than with some "in-your-face" brawler design.