I started a new playthrough of SoulSilver yesterday in which I have only Eevees and two HM Slaves (Blissey and another... probably Bidoof). [There is an AR code that lets you rebattle trainers' and gym leaders' first rosters by holding L and talking to them--best. code. ever.] I'll let you know which is the best after I play for a while.
Also, someone posted this on the Black/White boards. If you know the original artist, let me know so I can find more. It's new Eeveelutions. (too lazy to upload it to photobucket, so it's attached)