most say PMWF ( http://www.pmwf.com/Watches/WATCHSALES/WatchAccessoriesSalesTable.htm ) are the best, but they don´t come with a pearl. So everyone is saying to get an Ofrei pearl to put on the insert.
In my opinion, as I got both and a gen to compare with, I would go with a Yuki or PMWF Insert and a Yuki Pearl (which are out of stock right now)
Cheapest way would be this one:
http://cgi.ebay.de/BEZEL-INSERT-FOR-VINTAGE-ROLEX-SUBMARINER-5513-1680-/400110830936?pt=LH_DefaultDomain_0
from Mr. Slimball but you have to drill the pearl out to make it look bigger and nice. IMHO it is also OK.