For most business apps with power users, being able to present data in huge, fast-scrolling, filterable, customizable tables with colorful styling for elements

For most business apps with power users, being able to present data in huge, fast-scrolling, filterable, customizable tables with colorful styling for elements that require attention (un-acked errors, etc.) elicits more joy from users than anything else. A close second is when you enable performing actions on multi-selected elements. "We could never do that with [competing product]." If at any point in your product lifetime you discover, probably accidentally, that some users are habitually exporting data from the product and importing it into Excel, well, first, you should panic, and second, your product managers need to become best friends with those users. For every one of them, there are a dozen who wish they could do the same thing but can't figure out how, or feel like it's too much work, and an order of magnitude more who would have their minds blown if you put that capability in front of them.