I use and like DDX with Delta 100, a relatively recent combination for me. I like it, because this combination gives me a fairly long, straight-line curve, see here: (there was a url link here which no longer exists)
This means—to me—a more neutral-looking negative with more ability to control the resulting contrast under the enlarger, at a price, perhaps, of some by-default mid-tone "pop" that I see with 320TXP or HP5+ in XTol, both giving a curvier curve (posted here in the past, too). XTol is the only other developer that I still use. I have not plotted those two films in DDX though, yet.
This means—to me—a more neutral-looking negative with more ability to control the resulting contrast under the enlarger, at a price, perhaps, of some by-default mid-tone "pop" that I see with 320TXP or HP5+ in XTol, both giving a curvier curve (posted here in the past, too). XTol is the only other developer that I still use. I have not plotted those two films in DDX though, yet.

