People say - wish go explore take GL Conjurer. Autorescue angels and other usefull things.

Agree. But mages are hard to rank. You should allready know location of nice things. You should be ready lead the group to fine ranking location.

So what is the best explorer if we choose non-casters?

deffensive warrior with 100% Lore? duergar ap (can see and attack hidden mobs)? arial assassin with 100 lore? (fast, can fly, see everyone but camo)? Your suggestions?

1st - main parameter. It should be welocmed by groups. So he need not to lead or seat in guild spamming who group; tell Care to travel?;sigh; who group;tell...
2nd - bit less main - when he grow up he will be able to explore quiet good.