As is usually the case, it depends on your scenario.
The "best" aperture, which I will interpret as being the aperture at which the lens produces its maximum resolution results, will not necessarily be f/8. You'll need to check reviews of each lens that include MTF graphs, to determine the aperture at which your lens will provide the maximum resolution.
Then you have to realize that resolution performance is evaluated on charts, which are flat and have no depth. In practice, most people do not photograph charts, but 3-dimensional subjects.
Therefore, the sharpest aperture of your lens may not provide you the depth of field that you require for your subject. It will give you the best resolution, but most of your subject may end up being out of focus.
If you want to photograph a product like a camera, for example, you may find that filling the frame with it and using the optimum aperture will not allow you to keep both the lens and the body in focus. In such a case, it would be better to trade-off your top lens resolution for more depth of field. I've shot such images at f/22-f/32 and the loss of resolution due to diffraction was far less dramatic than it is spoken of.
Alternatively, if you have the time, patience, and tools, you can take multiple shots at your optimal aperture, focus each differently, and then stack them. See 'focus stacking'. This may give you the best result, but it may be hard to tell the difference from an f/32 shot if your goal is to publish the image in a journal.