My answer is really to "which languages am I comfortable with", not *most* comfortable, there should be like 1 answer to that (or 2 in C/C++ case).
I'm most comfortable with C/C++, by far I'd say, but I've done some work with C# and JavaScript, including professional experience, so I've included them too. I could really include Java as well since I had it in univ, I even TA-ed a course that used it, but since I hate it, I won't out of spite
I considered making C/C++ one category, however, I've been scolded enough by C programmers to realize that some people just find that offensive to group them together.
Long ago it was 6502 assembly and BASIC, then Pascal and 8086, now C/C++, PHP and JavaScript.
I really need to spend more time with C#, but we don't use it at work yet and I'm too lazy when the weekend rolls around.
I swear that MS Visual C# is psychic. . . it seems to correctly predict what function I want next from a single character and the tab key.
What, no object pascal?!? The blasphemy! LOL. Being honest, Dephi has one of the best IDEs in the industry.
Anyways, I chose C# and Java for their well established code base, developer tools and vendor buy-in. Also because I have established a fine-tuned development process with these languages that allows me to rapidly develop and deploy anything I want with minimal bugs.
I also chose C and C++ because those are what I learned how to program.
Delphi has a good IDE, but I'm still spoiled by Visual studios. I was going to put "Yeah, but what about eclipse" then I remembered just how crappy eclipse can be. The Delphi IDE is a good "It just works" IDE.
I forgot about Pascal. I really don't like it as a language. It does everything that C/C++ does, yet, it just seems so wordy.
Borland deserves some credit for inventing "visual" programming, and their tools always worked well. I did one of the first reviews of Delphi for Software Development magazine, I think it was the early nineties, and the environment already incorporated many of the features that have become a standard component of IDEs today.