I've tried a few different types of strings and found some faves. These are the top of the pile.
When they first came out, a lot of people thought the DR Neons would be a gimmick - just a "toy" string made to glow under black light. The DRs are actually high quality nickel wound and won best in show (strings) at the January 2011 NAMM show. They squeak a little when you're breaking them in, but it fades away soon enough.
Read my review of DR neon strings here on Thunder Row.
DR Extra Life Strings - Black Beauties
Gauge .45 .65 .85 .105
These are great - like their brothers, the Neons.
They feel good - I'd say they have a slightly sharper tone than the Neons.
D'Addario Flatwound Chromes
Gauge .50 .70 .85 .105
Flats are always a heavy, thumpy sounding string - they don't have a lot of treble definition, but you can get them to growl by upping the treble on the amp. I use the OVERDRIVE feature to wake up the bark on these strings.
But sometimes, thumpy and dark is exactly the sound a person needs. There's less noise on these strings than with a roundwound. No zipping or clicking. Sometimes I get experimental and play this bass with a violin bow. You don't want to do this with roundwound strings - it will eat through the hairs on your bow.
D'Addario Half Rounds
Gauge .45 .65 .80 .100
Very interesting feel and sound on these. They're as smooth as a regular flatwound string, but have more punch, like a traditional roundwound. They start out as a roundwound string, but then the manufacturer grinds off the textured surface of the windings, so the outside is flat.
As with the Chromes, they are not coated, but with a slick, polished surface, they don't really need it.