What is the best programming language? Depends on what you are doing. Over all, I'd say C, because it's the most versatile and there is a compiler ported to most devices imaginable, from embedded systems to mainframes.
What is the easiest programming languages to learn? I'd say C. Over all, C by itself is extremely small compared to other languages, the book written by the creators of C is only a couple hundred pages, as opposed to my C++ book which is around 600. The syntax is simple, and C syntax is used in many other languages which derive from it.
What programming language can do the most things? Depends on what you want to do. I'm going to say C again, because I'd say it's ported to almost everything you'd imagine/need, so it can serve tons of purposes. Especially with inline assembly, you can access hardware directly if you have to.
What programming language is the most fun to learn? Personally, I LOVED learning x86 assembly. The rawness to it really intrigued me. You have control over everything, and as tedious as it gets, I really liked trying to see how I can make my procedures as short and efficient as possible.
For example, it took hours upon hours of trying to shrink my bootloader from 520 bytes to fit in the 510 byte limit. (last 2 for BIOS signature). As frustrated as I got, once I managed to shave off those bytes the feeling of accomplishment I got cannot be put into words.