You're probably right then about Sammael compared to Rahvin, but there is room for debate on that point mainly because Rand had an angreal, but Rahvin had knowledge of Tel'aran'rhiod (and help from Graendal).

I still think that there is no debating that Graendal is AT THE VERY LEAST on level 5 of the women. If you want to put Sammael on level four of the men, then we can do that, but somebody has to fill levels 2 and 3. I'm willing to put Sammael plus or minus one level on the male scale as compared to Graendal on the women scale. But it wouldn't make sense for Sammael to be on level 3 on the men because that would not make sense with Moridin's comment. Somebody has to fill the male level 3 if it isn't Sammael. Possibly Be'lal? The guide does say Be'lal surpassed both Rahvin and Sammael in strength...maybe it meant one power strength all along and not just political maneuvering.

Possibly it goes like this:

100 - Rand / Ishamael
95 - Aginor / Demandred
90 - Be'lal
85 - Sammael / Rahvin option 1 / Balthamel option 1
80 - Rahvin option 2 / Balthamel option 2
75 - Asmodean