I'd personally go for a new bass.
However, it depends on what exactly makes you feel unhappy with and what you are trying to achieve.
If you want to explore new sounds and feel like experimenting, effect pedals may come handy. Thus, I'd stayed away from bass distortion for years until I finally got one, and it allowed me to look at heavy metal from a new viewpoint. At the same time, compressor turned out to be useless (for me personally).
If it's about the quality of your sound, here I can see three directions for improvement: your technique (especially plucking/picking hand), bass itself and gear. I'm not trying to say your technique is bad, don't take it wrong, but from my own experience I can tell you: my sound improved dramatically after I started taking lessons and realized my right hand had sucked for years. Simple as that. I don't regret any penny I've spent on attending teacher. It really was the biggest and most important upgrade I've ever done. Not a single bass or pedal I have ever bought made more difference.
Now, the gear (I mean amp/cabs). It's tricky. It has really much to do with your sound and if you have your own rehearsal space or take your own gear to the gigs, then by all means upgrade it if you feel like. If you don't and have to practice at home at 5% volume because of nervous neighbors, then...you see.
The bass. Squier CVs seem to get a lot of love here. If you are going to make professional recording or play big gigs on cool gear, then you may want a more serious ax, why not. I think getting a cool MIA Fender (or anything you like, not trying to do product placement here) will be a better hardware improvement than some pedal. Maybe better than amp or cab. After all, if you are in a studio, they will be likely to have quality gear. But you'll be using your bass, and the better it is, the better sound you'll get.
Okay, it's been too verbose. To cut it short, I'd go for either new bass or finding a teacher which has something to teach me to.