I love working in: C++, Objective C, C (in that order)
I tolerate working in: Java, PHP
I'm a bit rusty in: C#, Perl

Shells and languages I've not used for a substantial part of a real project don't qualify.

I'm at my best in UNIX-like environments, though I've done Win32 programming in C, and if you'd guessed the C# I wrote ran on Windows, you'd be right.

I believe efficient code is still a virtue. I don't believe in optimizing at the expense of maintainability without just cause, but far too often I see code written that is senselessly inefficient and harder to maintain (or bug-ridden).

Now, to hijack some quotes:

More computing sins are committed in the name of code reuse (without necessarily achieving it) than for any other single reason - including blind stupidity.

Premature abstraction is the root of all evil.

Rules of Abstraction:
Rule 1: Don't do it.
Rule 2 (for experts only): Don't do it yet.