IIRC, the top Forsaken were Demandred, Semirhage, Graendal, Ishamael, Lanfear and later Sammael. She has been included in with that bunch and we also know that she recruited Sammael to the Shadow. With regards to the series, she is perhaps the only Forsaken who has been contacting every one of the others. Asmodean met with her, she met with Mesaana, Demandred and Semirhage, she was forming an alliance with Aran'gar and had one with Sammael, she met in tFoH with Lanfear, Rahvin and Sammael and has seemingly worked her way into Moridin and SH's good books. In that, she isn't matched by any oher Forsaken and she still survived. No one managed to get the better of her.... until TGS anyway.

As far as dangerous goes, she is the only one of the Forsaken (except Semi, I suppose) to entirely destroy a nation. And, of course, she is the only forsaken to have killed another Forsaken.