this may be a little off topic....

ok so to answer the origional question: i usually try to use my eevees nature to decide what it evolves into....it may already have an advantage in a particular stat. As an example if the eevee has a nature that increases speed why not evolve it into a jolteon so it can max out its speed=)
as a rule flareon, umbreon, and leafeon use the attack stat and espeon, jolteon, vaporeon and eevees ice evolution use the sp. attack stat

and also i had a question of my own...ive had every eevee evolution besides umbreon and i desperatly want 1 but is it really that great of an attacker?

Umbreon is the best of the Eeveelutions, if you gotta ask me.

I'm not completely sure I understand the point of this, clarifying your orginal post would help, but Umbreon is NOT a good attacker, at least not until set up by curse.
As for your question, Umbreon's main function is wall support. With wish it can heal up other Pokemon in your party, as well as take a few hits and possibly allow you to set up and baton pass.

thanks snuffleoffagus for the advice and this too is a messed up post......im really sorry for the second time i ressed new topic instead of reply.....so im really sorry and i will be locking this 1 too. hopefully this is the last mess up

The only attack Umbreon could use to dent something would be Payback, umbreon is pretty slow so if it gets hit Payback gets doubled in power, and gets STAB support.

Your wish is granted. You wanted a lock, and I'll provide it.