A handful have far exceeded my expectations for sure:
---Tech 21 VT Bass: I'm an Ampeg tube snob, always have been, always will be. I used to think of digital tube modelers and analog simulator pedals as a joke. Then this came out. No, it's not got the same visceral rush and 3d sound as plugging into an SVT or B-15, but it does the sounds of recordings of B-15's and SVT/810 rigs pretty accurately, and has a butt-ton of versatility, and does everything from dead clean to full-on fuzz. It's a complex pedal to master and there is a learning curve for sure. But it'll do a heck of a lot.
---JohnK Modded Greedtone Overdrive Clone: I was looking for an easier-to-use and smaller dirt pedal than the VT to bring on roadtrips, heard a recording of this 2-knob beaut on John's website, and loved it. And if the bass boost switch mod wasn't enough to put this one over the edge, he also added an awesome 3-way switch that gives you the normal clean sound, the typical 5k Ampeg 810 low pass, and a 3k low pass that I call the Motowner. That way I didn't have to bring a separate pedal to eliminate tweeter highs when going through the PA. It's such a great circuit that every bass dirt pedal should have it. I'm in a band where all I use are basses with dead thumpy flats, and it's currently in a battle with my Ampeg Scrambler for flatwound overdrive supremacy. Both have their high points, but I can't decide which I like better. Speaking of which...
---Ampeg Scrambler Overdrive: I have a BA112 v2 that has this circuit, and it's a good little circuit but I didn't care for how you couldn't switch it on and off because it loses bass response the more you crank the drive. So I couldn't use it without an extremely mild dirt setting and clean blending, which I hate. The separate Scrambler pedal fixed that, added a treble and volume knob to the drive and blend controls, and it blows my mind. Seems to be a rather polarizing pedal, but having compared it to cranking an SVT into the dirt zone, I find the sounds are very similar, except of course for the slam of power tubes getting nice and toasty. No pedal compares to that, but it does seem to capture that sound and touch sensitivity very well.
---MXR Bass Distortion: A simplified version of the Fuzzrocious Cat (Rat) Tail, which is a Rat modded for bass. 'Nuff said. My go-to fuzz. It's got a boosted midrange that ensures that you will hear your fuzz in a dense mix no problem, unlike many other fuzz pedals I've used. But what really surprised me was how well it did as a barely-on overdrive. It does boost the mids in that mode, but it mellows out very nicely if you like that boosted mids OD thing.
---MXR Vintage Bass Octave: A Boss OC-2 clone in a micro pedal with more gain, better tracking, and a nifty little mid boost switch for the clean sound that I've come to enjoy as long as it's just slightly boosted from the clean sound. Had one when it first came out and it had a problem with making chattery noises after you hit a note. Then I read on here a couple months ago that they fixed that problem, so I bought another one, and it kills! The OC-2 lasted on my board longer than any other pedal, but it sits on the shelf these days in favor of the VBO. And as a bonus, the octaves have like 1.6 db extra gain from the OC-2, and the clean sound has a whopping 7 db of extra gain, so you can turn off the octaves and use it as a very transparent clean boost as well.
---Broughton Low Pass Filter: 3 or 4 years ago, I was complaining that Markbass didn't make a micro pedal with the VLE circuit in it, which is a variable low pass filter. I hate tweeters on electric bass and I wanted to eliminate everything above 5khz from my DI line, and the VLE was the best thing about Markbass amps as far as I was concerned because that's exactly what it did. So I challenged all the smaller builders to make one, and I would buy one from the first person who did it. A few days later, Josh Broughton contacted me, I bought the first one he made, and it was perfect! It ended up being the pedal that launched his foray into boutique pedal making, and I'm very proud of that!
Honorable mention goes to the MXR Carbon Copy analog delay, but only because I haven't found a suitable use for it on bass yet. But I certainly have for guitar! I love how the echoes degrade as they repeat, just like those old tape delays like the Maestro Echoplex and Roland Space Echo. Possibly the best analog delay I've ever heard, and certainly the best one I've used.