Yoyoing has reached a point where any yoyo that is released will pretty much be smooth. Very few yoyos are released as A-Grade that have serious vibe issues. You’ll be fine with anything, smoothness shouldn’t be your deciding factor.
To answer the question, like Xdohl said, any yoyo you get today will be just fine on the smoothness factor. Even if you do for some odd reason get one with a slight vibe that doesn’t affect the sleep time, that’s fine. If nothing else, it’ll give the yoyo a bit of character.