Boyyyyyyyyyy, Janus, THIS outta open up about 99.8 posts!!
Everyone will have a GOOD reason, "WHY" they line their 3-4wts. with so and so taper and you bet............. I'm no different!! Well, God KNOWS, "I'm DIFFERENT', but we're talking fly lines, right?
Anyhooooo. on all but three of my several light weights, I use WFs. I just like the way they load, better, that way due to their respective actions. If I want the so-called "finesse", that some claim, comes with the DTs, I either cast that way, or switch to a different leader/tippet set up.

On a couple of my 3wts and 4wts. I also have Wulff Triangle Taper "Long Belly" lines, which this year, I've learned to really like a lot. They'll cast with the load and weight of a WF, but also roll cast like a DT. And, even tho', Wulff doesn't promote this line, as such, I find it's a pretty decent little "wind cutter", as well!

Like, I said, everyone that weighs in on this is going to have their own opinions and they're ALL going to be the right opinions, too. Because we all like certain lines, on certain rods, for certain reasons. IF......... by any slim chance, you can take your rod to a fly shop and try out a few lines on it, I'd say will be the best way to make up your own mind, what you like and dislike!?!
Good Luck!