I'd go with Purina One.

There shouldn't be a problem with you switching him to an adult formula right now. Some people (especially those with larger breeds) feed adult formula instead of puppy because there is less stress on the bones. Puppy formulas make them grow at a rapid rate. The adult formulas allow them to grow at a steady rate.

Don't worry about what type of food you feed, so long as you're actually feeding him! We've been going through some money troubles recently and I've had to mix in some sample dog food packs with their regular dog food just so it'll last longer.