A .com with 0 link building will almost always start off on page 1 or 2. Even for a competitive keyword, at worst you are looking at page 3.
A .net or .org will usually start off on page 40.
After 2-3 weeks of link building, with a .com you are looking at a top 3 position. With a .org, after 2-3 weeks of link building you'll be lucky to climb up to page 2.
A .com will always be king, it's the most valuable domain name for a reason.