It depends on the person. What does he like, love and hate?
I think the best thing for nearly any first time WDW visitor is to simply walk down Main Street USA. Take your time, do not rush. You only get to walk down Main Street for the first time once and I have never met anyone who hasn't truly enjoyed the first time they walked down Main Street. Since he likes sweets, you could stop at the candy store but you might want to save this for when you are leaving.
Assuming you start at MK (nearly everyone does), the "fast" rides are the 3 mountains. On the other hand, if has has never been to a "real" theme park before, then POC and HM will probably be unlike anything he's ever experienced.
Assuming he's a roller coaster junkie, you should take him to EE, RnRC, and ToT.
A more detailed suggestion really depends on how many days you'll be there and whether you plan to park hop.
I would recommend getting to Magic Kingdom for the rope drop. There is so much excitement to be felt! Plus, it is nice to walk down Main St. with the cast members all waving good morning as you walk in too!
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