Choosing a stand to suit a particular bonsai is a bit like choosing a pot for a bonsai. We need to think about size, style, colour and shape. The top of the stand needs to be sufficiently larger than the size of the pot, to create a frame around it. A stand about twice the length of the pot, or a little smaller, would be suitable. The height of the stand is also important. If it is too low, the bonsai may be hard to see properly. The style of the stand needs to harmonize with the tree and it’s pot, so for a chunky, large bonsai, a stand that is fairly solid looking would be best, and vice versa. Color of stand is very much a personal opinion, however the colour of the stand could draw attention to the bonsai. Then things like the thickness of the stand top and the shape of the legs can affect the overall impression of the bonsai. There are quite a few variables, but the bottom line often is "If it looks right, it's OK".
These few photos may give you some idea of what may suit.
If your stand has a frame around the top, any bonsai pot you place on it should fit within that frame.
Note that cascade style stands can be used to display upright style bonsai as much as Cascade Style bonsai. Sometimes you may want the bonsai to be higher, relative to other elements in your display and using a cascade style stand is the way to do it.
Round pots are generally best placed on round stands.