I'm a huge fan of Oyshi as it is just minutes from my house. There is definitely something to be said about convenience! That said, the sushi is pretty damn good here as well. Much better than other AYCE (all-you-can-eat) places in town. Though I do argue with my friend about what's better between Oyshi and Sushi-mon so I'd call it a coin flip.
The only reason I didn't give Oyshi 5 starts is because of the service. Every once in a while you'll find yourself wanting to order sushi for 10 minutes or more because you haven't seen your server. Simple solution for this is to sit at the sushi bar. Nothing I would knock it down to 3 stars for because overall is still great sushi and a good experience!