What hooves said but it's really just a personal preference. Their no point in playing a character if you don't like the look of him.
Two trinkets is nice, but it's easy to get the insignia.. plus NE can fade into shadows.
I personally like playing as Tauren for the Stamina boost which is always needed during PvP. Tauren as well have War Stomp which is a stun, and we all need an extra stun. I really don't know much about Alliance mainly, but I can say when it comes to Horde Tauren,Orc and Undead all have it's ups and downs. If your looking to try something new pick up the Blood Elf :) Not only will they look cool, but using Arcane Torrent against PvP could be interesting.
Personally, i liked Bloodelf/undead. The racials for pvp are insane, and they look boss in war gear, alliance-wise, i'd say night elf/human.
PVE DPS: orc or goblin
PVE Prot: Tauren or Goblin
PVP DPS: Blood Elf, orc, UD, Gob (all personal pref)
PVP Prot: Goblin, BE, Tauren or UD
PVE DPS: Worgen or Human
PVE Prot: NE or dwarf
PVP DPS: Human
PVP Prot: Personal Pref, since you are probably FC and having 2 trinkets doesn't matter as DPS isn't your forte....I would still go NE, Dwarf, or Draenei tho
Human for PvE DPS? I can't think of a reason other than weapon Expertise. I would probably grab a Draenai for the hit rating over a human.