Bows....

Im pretty sure with out enchnting it would be the dadrea you would have to be like a lvl 20

Well, I have the OFFICIAL guide for Oblivion so I will look up weapon stats and give you THE best bow and tell you how to get it...

A Deadric Bow WITH Deadric arrows for a damage of thirty per shot although you could enchant the bow and arrows to make it even more powerfull
Hope it helped Kidfly

The Daedric bow is a really good weapon, but you have to remember they are difficult to obtain if you are lower level; and they are very heavy. Lets face it, being over encumbered is a nightmare if your in the wrong place and very annoying. Enchanting the bow yourself is the best idea, and it can be done once you have access to the Arcane university (complete all the mages guild quests). If you like the idea of the awesome looking Daedric bow (or any type of bow for that matter), you can put a feather spell on it, so it's lighter and not as cumbersome. If you don't mind the weight, then add some health draining effects. The more powerful the soul in the soul gem, the more powerful the effects, so don't skimp on that part.

If you just want a regular Daedric Bow it's pretty easy if you are a high level, but if you're lucky you'll come across an enchanted one like me that does way more health draining damage. Keep your eyes out for already enchanted bows because they're usually better. I would recommend getting Shivering Isles if you want the best bows and arrows ever(Amber and Madness). I think I remember getting a bow that had a bunch of poison and health drain effects from a Countess or something. Good luck on your search, and if you have any more questions please ask. I'm probably the most experienced here(level 45).

The best bow is a deadra bow enchanted with fire and frost weakness and
Fire and frost damage for ghosts and atronaches

The best bow, I have come across, is hatreds soul. Its found inside the oblivion gate outside chorrol. Semi-difficult to locate by the way, seeing as your looking for a door that does not appear on your map. After entering the gate, take off to the left, and follow a path around until you reach a lake of lava. After reaching this "lake" hop out on to the small isles and head SW. You will reach a small drop off, with a door at the bottom. Enter here and clear out the fallen tower. You will be rewarded with hatreds heart, a mace, and of course your main goal hatreds soul! These are leveled items and also respawn. You just have to find the gate layout again, or don't close the chorrol gate as you level. Hatreds soul, at lvl 25, does 35pts of fire damage, and drains speed 35pts for 40secs! Stopping most enemies dead in their tracks. Great for skill raising!