Jill and Haar are much better than all of them. There's no argument there.
Titania I have used. She was very useful in Normal, but didn't like her in Hard. Like I said...somewhere above, she can't take enough hits and doesn't dodge reliably enough, and her base stats for her level aren't great. I found her to be useless in 4-4, too. Truth be told, I didn't think Kieran was much better in Hard mode. These days I prefer not to use Paladins in Hard mode after Part 3 ends, except as backup if necessary.
Marcia I have tried twice. The first time she turned out quite well, but I got the impression that I may as well have just trained up Tanith as she's less effort. The second time she got Str screwed really badly, so I'd pretty much wasted my time.