Oven cleaner is very bad for a number of reasons, and should be avoided at all costs! If it gets in your electrics, you'll have a very sad time of it indeed! Of the substances you mentioned, Pine Sol would have my vote. Simple Green can be an effective degreaser also, but tends to be somewhat corrosive if not completely flushed out.
There are a number of commercial engine cleaning sprays available, but they are not particularly environmentally friendly, being composed mostly of petroleum solvents. I'd spray Pine Sol on full strength, brush and hose as necessary, and repeat if needed. Elbow grease is as important as anything. A good scrub brush can do wonders.