As Jim asks, what are your goals?
For reverb, there are a few different types: spring, plate, room, hall, etc. as well as additional features such as shimmer and slapback. Each has its own character and is better suited to certain sounds.
For boost/overdrive/distortion/fuzz, I recommend trying a few light overdrives first and seeing if any of them can accomplish the sound you desire. If you want more distortion, try a heavier overdrive before moving into the realm of distortion and fuzz effects.
I'd be glad to make some specific recommendations, but first: What kind of ukulele are you amplifying, what is your effects budget, and what kind of sound are you trying to create?