I'll keep this down to the top three each because I can write a novel on disappointing pedals
Commercial Disappointments:
Fulltone GT500 - the generic distortion sound of every digital multi-fx I'd ever toyed with.
zVex Box of Metal - it turns out that you can have too much of a good thing and is another validation of my "no amps that say Peavey and no pedals that say metal" rule
Orange Bax Bangeetar - at the time my most expensive pedal purchase and it had exactly one setting I liked and I had to crib it from the suggested settings in the manual. oversized and overbuilt construction for what is probably their solid state crush preamp in a pedal
Commercial Surprises:
Wampler Pinnacle (the OG, not the deluxe) - it does exactly as advertised which for amp in a box or signature sound pedals isn't all that common
Boss RT-20 - at the time I had a Leslie cabinet that just had the rotating drum (no rotating horn) and the Boss was surprisingly accurate and far less temperamental.
Catalinbread Adineko - once you dial this in to the proper settings it is silly accurate to the liquid delay they set out to imitate but then you get all the fiddly, experimental sounds too
DIY Disappointments:
Sagan Delay - I respect the hell out of the designer but I would have been happier with a larger layout ala deadendfx because of the amount of controls and the effects loop ... modulation was a bit over the top for me as well.
Low Tide Modulator - talk about wanting something to work out ... I really like the random modulation concept, I really didn't care for the end result.
Executive Fuzz - I love some vintage fuzz but for whatever reason, I don't love the Jordan Bosstone
DIY Surprises:
Karaoke Chorus - absolutely brilliant update to the CE-1 and my favorite DIY modulation pedal thus far
Hydra Delay - excellent fv-1 multi-tap delay that is only leaving my board because I went bougie over the summer on delay
ROG Umble - I wouldn't know how accurate it is to a Dumble as that's not really a concern of mine, but it is a really great overdrive that is quite tweakable from a DIY standpoint.