Well this has been an interesting discussion, guess I will throw in my 2 cents.
First, I will say that ram rushing can be a serious problem. You can be on the offensive with map control, killing the enemies outer farms, and he can just ram spam your base and force you to backpedal. Its a cheap and effective tactic, I do think right now that rams overperform for their cost. Especially the 300 ones.
So, in regards to nerfs, I would say that I agree with reducing their movement and attack speed, as necromancer suggested, and increasing their ranged damage against UPGRADED defensive towers to be on par with damage from fire arrows. I cannot understand why upgraded defenses of other factions should deal less against rams then fire arrow defenses, its illogical and unfair for that faction. The rams are fine in health, standard ranged armor and melee armor as far as I am concerned.
Also, something nobody has touched upon, Lothlorien can literally do nothing against a ram rush. Even if they have a horde of swordsmen defending their base, 10-15 rams with some army support WILL get in and destroy the citadel, thereby ending the game in defeat for lorien unless they have an ent moot. I know this is a bug, but it does demonstrate how much damage rams can deal before you are able to kill them. They need some kind of nerf, not necessarily health and armor, but something.
In regards to the Warg Sentry, I suggested a while back that it be moved to the defensive build plots of an Isengard base, and I don't understand why it wasn't. It would be a simple change that would REALLY increase the usefulness of the building. Its in the Isengard suggestions thread somewhere, if you want to read it
But yeah overall I see both sides of the argument and agree to a certain extent with both, so I think the best middle ground is as necromancer said, movement speed and attack speed nerf, combined with taking more damage from upgraded towers.