A great hand for hand evaluation.  

North passes.

East bids 1♣ 

South bids 1♦ 

West bids 1♠ 

North passes.

East should probably bid 3♠  as though 15HCPs balanced, the hand will do well in trumps. Aces are undervalued at 4HCPs (Queens and Jacks are overvalued - especially in trumps)). No values in the overcallers suit. Any Kings and queens in partner's hand will be on the right side of the stronger opposition bidder. 2♠  would be an underbid.

South passes and....

West has a little more than he has shown, is on the right side of the opposition strong hand so kings more valuable. So should probably bid 4♠. 

According to Marty Bergen you should consider five Qualities of a hand:
(1) HCP
(2) Over- and Under-rated honors
(3) Suit Length
(4) Dubious Honor Doubletons’
(5) Suit Quality

Here is a link to a great article on the subject Hand Evaluation