I use a Spark Go. It's got just enough bass amp configuration to get the sound I want, and doubles up as a good headphone amp for my guitar. That and the play along features which I use on guitar makes it worthwhile for me. But if I only played bass then I might not have chosen it. Also the effects are decent enough. You can add a bit of grit to your sound, and EQ, noise gate, etc.
Forgot to mention, I've got an old Vox amplug but it hisses like mad. Maybe the newer ones are better, or try a different brand?