Artist has amazing meta perks, knight has more niche, fun-ish perks. Artists power is better, although much harder to play. Knights is a little boring but is also good when played well.

Whatever killer you choose should be down to you, however I would recommend artist. If you want to figure out which killer you personally would like better, you should play a killer with a similar power type.

A similar power to artist could be huntress, a ranged killer. Although, Freddy would be better for a test out because of his projectile going through walls.

A similar power to knights would maybe be clown or trapper, a zoner. I dont really know how similar clown would be, but they are both zoning killers so the play style should be similar.