useful (good and beneficial for a practical purpose): This tool is useful for gardening.
handy informal (easy to use or handle; useful): It’s quite a handy little toolbox. This cardboard box may come in handy.
practical (useful or suitable): I need some practical advice on which car to buy.
of use (useful): I found nothing of use in this place.
functional (designed to be practical rather than attractive): The kitchen was functional and simple.
helpful (useful, beneficial): Any helpful suggestions would be appreciated.
usable (can be used; practical): The equipment was still usable.