Want to sound like (insert name here) ? Read this! (DB forum thread)
Strings are a big part of your sound, but they have to work well on your bass to help you sound like you want to. They are only a tool.
As a reference point, find out what strings you have on now and go from there. This may help:
http://www.quinnviolins.com/qv_stringidsearch.shtml
Once you discover what you have now, do a search to see how most people think those strings sound like on their basses. If, for example, you have old arco friendly strings and want more pizz response you will be better informed. Strings are expensive and you won't want to ride the merry-go-round. If you do wish to experiment, try to buy used.
FWIW, spirocores are the default jazz string and hdiddy gave good advice.