I won't go as far as to say Archer is the strongest servant... But I do think the Archer class seems to be much more h4ax0r than the saber class. I mean seriously... Gil and Archer are both way too good.
And as far as the Gil vs Berserker fight is concerned, I wouldn't even call that a fight. Gil was forced to use enkidu you say? lol... the only reason he was "forced" to use it was because he wanted to show them how superior he was. He could have used hit and run tactics, or just back off a little... he just didn't want to move from his spot to show them that he can beat the "strongest" servant without even moving from his spot. That's just his character. By the way... using enkidu isn't a big deal at all. It's not like it costs him anything, or that it is straining on him. If he had used Enuma Elish it would have been different.
On Archer sniping Berserker... we don't exactly know if Berserker was killed or not by the blast. Even if he was killed by the blast we would have no way to know, since shirou didn't know about god hand at that point. He just saw Berserker come seemingly unharmed after being hit by an at least A blast. God hand can't protect him from that, for sure. So it means Berserker did regen by the time the dust has fallen. But we don't know the extent of the damage he received. Was it fatal or just very damaging? But he certainly received some damage. Ilya has even changed her target from Saber to him after that. Meaning she considered him a bigger threat than Saber.
And Saber would have never survived that sniping. As the dead ends proved.
And about Archer's eye of the mind... you guys are misunderstanding it IMO.
Maybe I'll put it into this
you can predict the path of a bullet, but you lack the ability to dodge it.
It doesn't work that way. Once the bullet is shot and he doesn't have the ability to react to it. It's just too late. The eye of the mind is useless as you say.
But he can predict all the actions before the bullet is shot and chose the action that would make it so that bullet is never shot. That's how it works. Of course, he can do that only as long as there is an at least 1% chance to avoid that outcome. If that outcome is 100% predetermined he wouldn't be able to change it.
His previsions from the eye of the mind(True) work on a much longer time line. This can be shown in how he spared Caster in UBW so that he can use her much later to break his contract from Rin. That's his eye of the mind working there.
So let's suppose he's going to fight Saber, he might not be able to survive an excaliblast... but he can create a situation where Saber won't be able to use it. Like the one in UBW too. Where he forced a stalemate by showing that she would kill both Rin and Shirou if she used it.
And even if he can see sometimes an outcome, he may chose not to take it. Like when fighting Ilya, he probably knew what exactly to do kill her and by extension Berserker. He just didn't want to. For him, Ilya was more important than beating Berserker, he still managed to accomplish his job as Rin's servant by killing Berserker 6 times to make things easier for her later on. He chose the next best thing since he didn't want to use the best one.