Hey dude!
There is a little debate regarding whether or not Melon farms are as efficient as Pumpkin farms. You see, because Melons have dropped down in price by 50%, it may be most efficient to use Pumpkin farms. The reason for this is, even though they sell for less than Melons, they give one block back, so if you break 64 Pumpkins, you will get 64 Pumpkins, where with Melons you are not guaranteed this, as in order to make one Melon block, you need 9 slices of Melons.
You should really take a look at this forum that I posted:
http://www.opticraft.net/index.php/topic,9172.0.htmlI had a full inventory of Melons, and I only got 4 stacks of Melon blocks
. If I had done it with Pumpkins, I would have made more money.
So, in my opinion, go with Pumpkins. Melons may seem the right way to go but trust me, go with the Pumpkins.