Using guides instead of making up your own builds/adapting to the enemy team comp... Yay for common sense!

I honestly like Solomid better. Their guides are approved by 'higher up' players, whereas Mobafire just has a lot of guides by not-well-known people. However, you should NEVER follow the Item builds to every single item. Every game is different. I usually don't follow the item builds on websites like LeagueCraft, Mobafire, Solomid, etc. Instead I experiment with my own builds. I only use them for the jungle paths (not that much anymore) Masteries and Runes.