I use firefox mainly. I am in to open Web development so I test in all.
Things I do not like about the other browsers (Stable releases only):
Firefox: No SVG font support, Very poor SVG animation by SMIL, No WEBM support, SVG filescan not be in IMG tag (OBJECT, EMBED, and IFRAME works).
Google Chrome: No Alternate stylessheets support, no MathML support, remote fonts disabled by default, and the simple interface (I feel it takes less control from me.), no Animated PNG support.
Opera: Poor UTF-8 support (Most characters are misinterpeted), Problems displaying certain Unicode characters (I have the fonts but still insists on showing missing glyph).
Safari: Dependent on Quicktime for HTML5 media.
IE: Where to begin... Poor security, No XHTML (application/xhtml+xml) support. No SVG support. No native MathML support. Almost no HTML5 support (IE Supports contenteditable attribute),
No HTML5 Media, no Canvas support, and no animated PNG support.
Things I like:
Firefox: Best extensions, Can use SVG effects in HTML and XHTML. is very customizable.
Google Chrome: Fast loading of pages and opening.
Opera: Best SVG support (Only browser that supports SVG 1.2 tiny), Advanced Web toolbar.
Safari: Best Canvas support.
IE: Sorry, I can not think of anything about this other than it went against web standards until IE 8.