I agree with those saying that good technique reduces the demand for gear and that an active tone stack on your bass is a lot already.
If you're DIing to FOH, I may add that there are some nice always-on effects to consider.
I would consider an amp-sim pedal such as the tech21 VTDI simply for its ability to be flat if desired (I've had alot of success with it). The treble roll-off of amp sims tends to be steeper than the tone knobs on basses (2nd-4th compared to 1st order). This may be desirable. Many also feature some bass roll off in the subs which can help tighten the tone, especially for bass heavy genres like reggae. OFC the EQ controls on pedals may be different from those on the bass which can be helpful for added versatility. Obviously, a bass cannot distort on its own (except for the darkray I guess) so any amount of warmth to overdrive is an added feature commonly available on these types of pedals. With warmth rounding out transients which is often desirable for smooth and inobtrusive sounds.
While note evenness can be largely addressed with good technique some other thoughts are:
Compressors can also shape the attack/sustain characteristics in ways that playing cannot. You can set a compressor for fast attack, release to squash just the attack of notes for a super sustained sound which cannot be done with RH technique. Inversely you can set a slow attack and fast release for added percussion. Alternatively, you could play like Geddy (who themselves has a lot of fx) but then you're contending with fret buzz, strings bottoming out on the PUs and potential for fatigue and tension in your RH.
For compressors, I hear people swear by the Empress Bass Compressor and some more niche picks. A website called Ovnilab has one of the most comprehensive compressor review archives I know of.
Otherwise, there's situational effects such as fuzz and chorus. As others have said, these are just for your wants and tastes. One consideration is that without an amp or amp-sim, many distortions/fuzzes may sound too bright because they are designed to be followed by a treble roll-off of an amp.
I will say many people seem to swear by the way-huge pork and pickle drive and frankly I don't have much experience with choruses but Boss products are usually pretty good so maybe a CEB-3.