no contest here lol....SHANNEN kicks ass
okay....i think its pretty obvious who the better actress is. lets review a few movies done by each of them.
Shannen Doherty:
The Rendering: very suspensfull and edgy. she had a very stylish appearence in this movie as well.
Another Day: another dark, complex movie with a very interesting plot.
The Battle of Mary Kay: who knew Shannen could have such fun playing a character like this without even TRYING to be funny?
Satan's School for Girls(2000): a nice remake of the Aaron Spelling classic (produce by Aaron himself). Shannen's role was rather similar to that of her character Prue Halliwell...but the movie was still a fun indulgence.
now then..
Alyssa Milano:
Poison Ivy 2: the sequel was rather pointless since the main character of the original movie DIED...and no one from the original movie returned for the sequel...
Embrace the Vampire: straight up GARBAGE....might as well have been soft core porn
Fear: the only DECENT movie she was ever in (imho)...her character was rather one dimensional...but still provided strong support to Reese Witherspoon.
.........oh wait...thats all she's done! oops...guess there's nothing left to say on THAT lol
Alyssa Milano is an actress who really got over on the fact that she was a child star of the 80's...and people were intrigued by her return to TV in Melrose Place. She wasnt even FIRST CHOICE casting on Charmed...and yet now a days..the show's last few seasons have been so "phoebe" centric...that many viewers have jumped ship..including me

When charmed was first created....the role of Prue was MADE for Shannen..it gave her a chance to dispell the "bad girl" image she had cemented on 90210 and in her own life off screen. Shannen's acting skills were evident and even Holly Marie Combs said that she gave 110 percent performance.
Prue had the best powers, the best look of the sisters in terms of style and wardrobe and she was the leader of the sisters who spurred them to ACTION..instead of REACTION...which is what the current group of sisters does best. They now spend their time screaming, getting thrown into walls, and running around tables from demons...depending on spells and potions rather than their own powers. Piper, who is now the OLDEST , often takes a backseat to PHOEBE..what kind of shit is that? and its obvious that since Phoebe lacks in "power" the other two sister's have been "dumbed down" so as not to outshine her. when PRUE was there...the sisters were fast, quick thinking and confident in the use of their powers.
there's DEFINATELY no contest here....Shannen/Prue Halliwell was/IS the best Halliwell there was.