Seems like one of those questions that can be answered on many levels!

In the broadest sense, I would say the "best" ideas means finding out something a person genuinely and really wants but they would never consider buying it for themselves. For example, I bought my wife an iPad many years ago... and it turned out to be the best gift ever, pretty much for those reasons: It was unexpected, she loved it, and she would never have gotten it for herself. Maybe not even today, where they are a more essential part of life.

In a more specific sense, I have often found that gifts of FOOD and DRINK are greatly appreciated, especially if you know someone's tastes. Maybe that's also a reflection of my age (57) and who our peers are now... we're less into "things" and more into "experiences."