I don't use them (the closest I've gone is experimenting with the different resolution/aspect-ratio versions of the default ANSI-like character set, but I change very little (a few worldgen params (larger gaps between layers), Seasonal saves/backup, water levels as numbers, no music (shame!) and no intro (even more shame!)) and put absolutely no thought into trying out 'graphical' tilesets, as opposed to the 'non-graphical' ANSI-like.
Except... I did see a tileset in a screenshot recently that I like the look of. The stylised nordic-runish standard letters weren't my thing (though they were well executed) but the walls tiles in particular, were much the same as the "double-rail table border" ones of the default, but with diagonals across 'elbows'. Like (although not particularly like, because of the limitations of the ASCII that I'm using in these expansions) the right hand item of the following two traditional symbols represented on the left, for up/right bend and up-down/right spur pieces, respectively. (If you can't tell what they're supposed to be!)
|| \\
|_= \
|| |\
| = |
|| |/
Anyway, although the above doesn't do them justice, I liked their way of dealing with corners. (Would also work well with a staggered diagonal wall, I suppose... Hmm....)
If I were to change, I'd either hunt down that set or plagiarise my own personal wall-set with the same idea in mind. But I don't see me doing that, traditionalist and stick-in-the-damp-silty-clay-loam person that I am.