Unique has been around over a hundred years and there's a ton of data for it. It does work very well in light to medium loads across a very wide range. There'll always be a can on my shelf because I can make anything work with it.
There is one drawback. It does not meter well. Unless you have the patience to scale every charge, which I don't, you won't get the very finest accuracy from it. That don't much matter. Even with the variation of thrown charges, it shoots well enough for my purposes most of the time.
I can understand the vote for 2400, though. It covers a slightly hotter range than Unique and is better suited to hunting loads. Been around a mere 60-70 years, and there's a ton of data for it, too.
Truth to tell, it's the data availability that's important. Life's too short to go working out your own data for every possible powder. Many of them work very well once you have them figgered out, but 2400, Unique, and a few others are already known. So many shooters have used them in so much stuff that you can have a real good idea where you will get results before you throw the first charge.