Predator Tools has a good selection of high quality shovels that are made in the U.S.A.
I own several different models and can say without any hesitation that the build quality on each shovel has been top notch.
To some extent the shovel you choose should be chosen in conjunction with the primary type of detecting you think you'll be doing.
Some models are smaller and less intimidating, which work well in park settings, while others have larger longer blades with serrated edges useful for getting through tree roots in wooded areas. A wider blade, that can move more material, might be preferred for farms fields. In the end, build quality, handle type (D or T), total length, blade length and width, serrated or non-serrated edges and overall weight are just some considerations to consider.