I think the Fender P & J and the Stingray are still the benchmark by which other instruments are judged, all are regularly available on here for under a grand and are the basic instruments that others have improved/butchered depending on your take on things.
There are not many genres you couldn't cover with a P, a J or a Stingray, so you could do a lot worse than choosing which ever is appropriate for the style you are playing and you'd have a bass for life.
Personally I've craved the Wal sound since I first heard one and that is the tone I have in my head that I want my bass to sound like. I've tried several combinations of bass and amp to get there but in the end I have bitten the bullet and ordered a Wal... Will it make me a better player? No of course it won't but it will give me the sound I want and that will make playing more enjoyable, which for me is what it's all about.