This is the original release of Ego Draconis?
The Bow of Tiberius has a +1 bonus to Ranger Strength, if you don't already have it maxed.
The Ultimate Good Bow has 3 enchantment slots, rather than 2 for Tiberius, though after the normal and magic damage enchantments, there isn't a really compelling third choice (Butcher is ok).
I'd go with the best damage; check both (the skill bonus may or may not make a difference).
Don't worry about the hit points; add Life Line enchantments to armour for that. With Ranger Stealth you should be getting the first hit in most of the time, and be far enough away to avoid taking too much damage (Level 1 of the Healing skill and potions can make up for a slightly lower max HP).