For me personally? I like pg's philosophy for Arc, I like his emphasis on short code, short variable names, I like ssyntax, I like how a large portion of Arc is written in itself, I like it's polymorphic nature (you can call a table with the key, call a list with the index, etc.) I like Arc's emphasis on hackability and not trying to restrict the programmer. I like that macros are just annotated functions. I like unhygienic macros, though I have been thinking about alternatives.
There's actually quite a few small little things I like about Arc that I haven't seen in other languages. Those small things can add up, ya know. Do other languages (such as Scheme) have those things, or are at least capable of adding them as a library or something? Probably, but it's hard to explain...
I don't like Python. This might seem kinda strange... Python at first glance appears to be a fine language. It has nice clean syntax, a good standard library, plenty of popularity, a decent class system, first class functions, and Py3k even adds in proper closures! Yet despite all the nice things Python has, it leaves a bad taste in my mouth. Maybe it's the terribly gimped lambdas or Guido's rejection of functional programming, I dunno.
Anyways, I can list a bunch of different reasons why I may or may not like a particular language, but I think a lot of it is just gut instinct. Arc just feels right to me, in a way that Scheme/Common Lisp/JavaScript/Python don't. Then again, I haven't written much Scheme, and have written almost no Common Lisp, so take that with a grain of salt. :P I might warm up to those two if I used them more.
A lot of JavaScript for... I dunno, 5 years? It's been a long while.
Dabbled in bash (ew), have some Python experience (way better than bash, but still ew), haven't programmed much in Arc[1], but I love the language. I've also written less than 100 lines in a few other languages.
That's about it, unfortunately. I've read about plenty of other languages, though, ranging from Java to C# to Haskell to Smalltalk. I've been pretty interested in Haskell lately, I might try that out sometime.
So... primarily JavaScript, which I'm thankful for because it's actually a pretty nice language, once you get past the cruft and warts. It has proper lambdas and closures, unlike Python! The DOM's an absolute mess, though...
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* [1]: It's a lot easier to just discuss it. Also, I've been spending my time writing an Arc interpreter in Python so that I can eventually program in Arc. :P It's been a pretty fun learning experience, though.
