Since you can really only have one job at a time and maybe like 10 total jobs over your whole career, optimizing for the biggest pool of possible jobs doesn't n

Since you can really only have one job at a time and maybe like 10 total jobs over your whole career, optimizing for the biggest pool of possible jobs doesn't necessarily make sense. Obviously don't pick something esoteric, but if you have years of experience in any of the popular languages (Java, C#, Python, Ruby, PHP, JavaScript, etc.) there will be plenty of jobs for you. Optimize for whichever language you don't mind working in for years at a time.