^This list is about the best resource as to whats out there right now.
A lot of them are very similar as they use the same chips, just look for what you can get the cheapest as cost/performance ratio on these is about the worst compared to bigger miners. Usually every new type of chip will see a wave of USB miners using them.
They are ideal for beginner miners wanting to see what its about and/or as a hobbyist not too concerned with profitability. Just understand you will by no means get rich with it, or even make back what you spent.
I do see a couple advantages to them however that I think bigger scale miners overlook-
Easily replace dead chips, as its one per USB stick
Easily upgrade USB rigs with newer chips using the same USB hubs
For smaller miners, it also makes one more able to step up your mining abilities without huge investments.
So, you do sort of pay a premium up front, however there can be some back end cost/maintenance savings. Just do the math and see what works best for you and your budget
