I've gotten myself into several areas, all on Microsoft platform, starting out with Dreamweaver myself. ASP was fine for me for a long time, and for a lot of the intranet designs I've done this has been my best choice, and now progressed to ASP.NET but now using Visual Studio - a whole new game for me. However, it depends on where you are looking for your clients and what hosts are predominantly offering, and this I find personally to be along the lines of PHP.
I tend to steer clear of client-side scripting like Javascript, and since I only use it for the extra effect on a site, I don't consider it as valuable an investment of my time to learn it more. Why not give a few a try? Like myself, familiar with most but proficient in one I think is best.