Prophecies is long and boring. Post-searing Ascalon has a horrible environment (it was good the first time through after joyful presearing, but now its just dull), and the shiverpeaks aren't much to look forward to. Difficulty-wise Prophecies areas in general have been left in the dust and there is no challenge what so ever. Its also really long to play through. Character designs you can make in Proph also, for the most part, look worse than those in other campaigns. You are forced to play well past LA just to get your character points, which is annoying. Did I mention prophecies was long?
Nightfall sucks. Sand. Sand. Sand. Sand. I hate sand. Just the Crystal Desert in Prophecies was enough for me. It would be much shorter than prophecies, but then Anet forgot that they needed to pad out the game length and required title grinding to pass stuff, so it ends up being not all that much faster then prophecies (and much slower than simply running from Ascalon->LA). The mere fact that a non-nightfall character doesn't have to grind sunspear ranks is enough reason not to start here.
Factions is excellent. Fastest leveling, Great atmosphere on the island, and the rest of the game manages to take you to new locales quickly enough to prevent you getting bored (which Nightfall epicly fails at). Enemies are respectably deadly (unlike prophecies) without being infinity-bullet sponges with too many defensive skills (unlike a number of enemies in nightfall). Zen Daijun gets points for being the only early game mission that actually requires some sort of skill to pass, and missions in general are better about not wasting my time doing stupid crap like other campaigns. Then as soon as you go to Nightfall to get your heroes you can go right back to Cantha and complete 5 or 6 ferry quests in about 20 mins to level yourself and them to level 20 quicker than a Nightfall character could (and when you want to go further in the Nightfall campaign to get more heroes you don't have to deal with the motherRED ENGINE GORED ENGINE GORED ENGINE GORED ENGINE GOing title grind). Factions is simply the best. What more could you want? Ahh, I guess you can't start Paragons or Dervishes there, but who uses them anyway?
