I would hope that we all agree that tone is both in the fingers and in the gear. This thread is specific to EQ. As stated earlier, if it's a struggle to get a bass to sound good using EQ, then it's probably better to get another bass. However the same is true for technique: if you have to go outside of your comfort zone to get a bass to sound good -- e.g you have to play too hard, play too close to the bridge, etc -- then you should likewise consider getting another bass.
There are other factors such as setup and strings, but let's keep things as simple as possible and assume they've already been optimized...
Or work on your technique. That's usually free.
Technique and EQ. Both are free.
No really P...