I've been using a fender active deluxe jazz bass for a year now, and (to my shame) I have yet to change my strings. I always postponed this cos I wasn't too sure which strings to use, but they sound like sh*t right now. So could anybody give some advice? I play red hot chili peppers, john frusciante, arctic monkeys, jimi hendrix, interpol, some jazz, etc.

Thanks in advance.
kaas... sounds like youre dutch!
It kinda really depends on what sound you are aiming for. you want a nice fat sound go for nickelwound, you want something more aggressive and with more high harmonics go for stainless, you want something real smooth go for Flatwounds. If I were you I'd go for standard gauge, or if youre up to it, a bit thicker. the thicker string the better the sound!
Since you like to play Pepper stuff check out GHS BassBoomers
Personally I like Dean Markley Blue Steel strings. I have a set from '95 that never lost their tone, though that bass was in a closet for about 12 years. Still spent a good year or so playing with them before it became a closet case.
1978 Peavey T-40 -> Ampeg Micro-VR - > Ampeg SVT210AV + Ampeg SVT-15E
For a very broad spectrum of music your safest bet is probably just some standard 45-105 or 40-100 gauge stainless steel or nickel roundwound strings. There are plenty of reputable brands to check out... Rotosound, Ernie Ball, Warwick, D'Addario, DR, etc. The best thing you can do is experiment with different brands over time and eventually you'll find one that really works for you.