First of all, I would like to mention
Henning's Passion. Mandatory listening.
Of other recent pieces, there's a
Passion by
Knittel, which was received very well over here, but for some reason I can't "get into" it.

I guess no one (apart from me) knows
Jozef Elsner's Passion. I like it well enough, though not being exactly well-versed in music of that style/period (don't even know Haydn's masses well) I can't really offer an informed opinion. Should be interesting at least by virtue of it being composed by Fryderyk Chopin's teacher.

(The one I know must be a different recording...)
It's odd to realize that the Passion I have been most faithful to over the years is Penderecki's... I truly love Bach and listen to his two a lot. And yet, despite the fact that I have "only" one recording of the Penderecki, it has somehow gained precedence. I do not listen to it as often as to Bach's passions - but I listen to Bach's at various moments in the year, while the Penderecki I associate almost strictly with Lent.
BTW, since the Stabat Mater sequence has been mentioned as well -
Szymanowski's Stabat Mater, along with his
Litany to the Virgin Mary, have got to be among the most beautiful things he ever composed.
And speaking of
Penderecki, I have made a habit of listening to the second part of
Utrenja (Resurrection) on Easter mornings.
Very odd - I don't listen to Penderecki all that much, generally. But these two pieces of his appear to hold a surprisingly important place in my listening.