I like the Buffy one better.
Here is the Jeanty cover for Angel & Faith (spoiler tagged for size):
Two more covers were revealed at the WonderCon panel - so far we only have the screenstills from the video on Youtube:
Steve Morris cover for A&F:
Jeanty cover for S9:
I like the coloring and Jeanty's drawing of Buffy here, much better than I did in most of S9. His Buffy often looked too childlike, but he got better in #40.
"25" probably refers to the 25th anniversary of Dark Horse. Or maybe the 25 issues that both S9 and A&F will have. Or 5 x 5.