Nimo Sunrider would kill Mara. I haven't read tales of the Jedi, but didn;t she stand against Ulic for a while and eventually bring him back to the light. Since Ulic on one thread that I made was beating Mace by a good margin, I think Nomi would win.
Exar could probably beat Vader during anytime. I think that Vader is very powerful but he never reached a lot of his potential since he took a lava bath at age 21. Think about how far Obi-wan went from TMP to ROTS. Obi-wan was 26 in TMP and got several times more powerful from TMP to ROTS. Probably more than five times as powerful. Think about how much more capable Anakin would have become in five more years of traing, much less another 13 like Pbo-wan. If Anakin had been training since birth, stayed a padawan until maybe 25 and never took a lave bath, imagine his capabilites at an age like 40. One word. Badass. He would also have become much more emotionaly stabel and have had less problems from the start. He would kill anyone. Mace,Yoda, Revan. Anyone. The force would probably have also sustained his life for several hundred years. With all of that time to learn Jedi ways. At an age of maybe 500, he might be able to kill Yoda, Mace, and Palpatine by himself.
Sorry for the rant.