and do I have to be 20 to get them?
and which is the best?
where can I get heroes?
Methal
sixdartbart
http://wiki.guildwars.com/wiki/Heroes
this will fill you in on where and how to pick them up.
as for "which is the best".
That is entirely up to you, you setup their skill bars/runes/weapons
this will fill you in on where and how to pick them up.
as for "which is the best".
That is entirely up to you, you setup their skill bars/runes/weapons
Quaker
You need to own Nightfall or Eye of the North to get any heroes. If you have Nightfall, I think you get the firat few fairly early on if you start in Nightfall. If you have Nightfall or EotN, but started your character in Prophecies or Factions, you'll need to get to Lion's Arch (Prophecies) or Kaineng Center (Factions) to get the quest to travel to Nightfall or EotN. You don't need to be level 20.