I always build both. The silk touch, as has been mentioned multiple times, is great for long mining trips due to inventory usage. It is really quite easy to drop items that yield better with fortune into a turtle that keeps placing as you break with the fortune pick in front of an obsidian wall. Best of both worlds.
There even used to be a block you could actually place a pickaxe in and it would automatically swing it at blocks in front of it. Not sure if it is still around, but that would have made for a really nice automated turtle fortune processor.
There even used to be a block you could actually place a pickaxe in and it would automatically swing it at blocks in front of it. Not sure if it is still around, but that would have made for a really nice automated turtle fortune processor.