Honestly dark knight strikes me as the most important crystal wheel, and as for samurai, the slopes are kinda bad as a bottom wheel. For attack, dk aside, I imagine that my rule about clear wheels also applies : Not blocking metal is the biggest thing, followed by putting weight behind contact points. This would likely mean it would depend on the chrome wheel. For others, probably whatever has the best balance for that chrome wheel, unless the shape has major advantages/disadvantages.
Chrome wheels are in the same weight range as pre basalt/hell metal wheels, so those would be good testing opponents imo (especially as we know a lot about them). That's what I've been using them against myself anyway. As we don't have much data on unsynchromed beys, using them as opponents introduces another uncontrolled variable making results difficult to interpret.