Which heads to get?
Magnummopar has an excellent point. What are you doing and where are you going and is there a possible future of going to a higher level of performance? If your planning on building an engine without the possibility of expansion, then a certain head will fit that build and then that will be that. Obtaining more HP might require another head. As if the future head choice is all ready a ported head. If you need more head, then your stuck with a new head purchase.
There is nothing wrong with an iron head. Again, a lot has to do with the intended purpose. Or sometimes the rules you must fit into. Like "Must have a iron head"'in order to compete. This rule leaves you with a stock factory production head, the above mentioned, W2's. Now factor in cost.
One of the things that bother me about a lot of people is there screaming aluminum head all the time and point to weight savings. While a good idea, does a street mill even care about 50lbs. when a time slip is not in play?
1 point of compression is worth 3%, generally speaking. So if you build a 400HP engine, the aluminum head at 1pt. higher in ratio (head flow being equal) will make approx. 412 HP.
Something you'll never notice or feel on the street.