You should always choose which classes you really want to play in the end, regardless of heirlooms, race, faction, starting zone, or other factors which become irrelevant very quickly. Gear drops everywhere and you'll get it anyway especially if you're doing dungeons.

Personally I have 5 sets of cloth heirlooms, including the guild ones - helm, cloak, and pants. The stats are so inflated that it doesn't make a huge difference, and the rest of the pieces can be filled with gear appropriate for the class. I have some misc. pieces - plate, leather, caster leather, 5x 2 handed swords, and some trinkets I use occasionally but the heirlooms are really for the experience gain and max stats (it's like wearing the top tier epic at every level).