There’s no universal criterion to determine this, it really depends on the case. If you examine the advantages and disadvantages of these two solvers you will be able to judge which one is more appropriate for specific problem.
In general explicit works much better than standard in case of high speed dynamic events. It’s also better for large deformations and complex contact conditions. Its ability to handle severe nonlinearities makes it very useful for quasi-static analyses of metal forming processes as well. But it has some disadvantages that make implicit better for low-speed, mildly nonlinear problems.