F/SN Servants are usually stronger, with exception of Archer and Saber was feat in that fate route than in Zero or other route.
ISKANDAR FOR THE WIN!!!!!
I'm more inclined for the Zero Servants
Archer, Berserker and Rider are forces to be reckon with
Herc destroys Iskandar without losing a life.
But yeah, Iskardar and Gil should be the only two stronger than their later counterpart
Saber was in both Fate/Stay Night and Fate/Zero, so I don't know why she just isn't taken out, but let's go along with how she is on the fate/stay night team.
Saber will beat Gilgamesh, Lancelot will kill Saber, Stay Night Lancer can kill Lancelot and Zero Lancer, Iskander will drop Fate Stay Lancer and Fate Stay Assassin and Rider, but possibly lose to Fate stay Caster. Fate Stay Caster will probably lose to Zero Caster, giving the win to Zero.
@Galenbeta: The way Avalon works is that the sheathe surrounds Saber in a barrier that isolates her from the physical plane of existence and provides her with a defense that counteracts any destructive effects coming from various planes of existence and parallel dimensions, and reflecting the effects of said attacks back at their senders. The only setbacks with the sheathe are that Saber can't attack or move while Avalon's abilities are in effect and she has to trigger the sheathe's effects to activate them. This would pose an issue for Saber if she were up against a significantly faster foe who could dispatch her quickly than any chance she has to react or dealing with multiple powerful foes attacking her at once. But with the Servants in this match being on par or lower than her in speed and multiple characters being allied with her in this match, both these weaknesses aren't an issue here, especially as Archer being here allows him to counter GoB with UBW.