How to choose the best:
Radish

Touch

Look for a nice firm firm root, and any avoid any radishes that are squishy or soft at all.

Another good sign is the skin — which should be totally taut over the radish’s surface — so avoid any wrinkly specimens.

See

Look for brightly colored radishes with well-colored greens attached to the tops.

Keep an eye out for any white, black, or brown spots, and avoid any with yellowing leaves atop.

Some more details:

When it's in season

Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.