I like my german e-tool with forged folding spike on the back.
it's got a square push button lock that works well in all 3 positions.
quicker and easier to use than the US screw style locks -- but it's also heavier.
of course, if folding is a want and not a requirement, the $6 miniature D-handle shovels at your local hardware/lumber store are pretty decent, too
the Cold Steel special Forces shovel is another good option under $20.