Oh, I think it would be 好きな食べ物. Oops. Also when I typed it into Google Translate to see what it came up with, it said マカロニとチーズ when I said "My favorite food is macaroni and cheese", but then when I put "Macaroni and cheese is my favorite food" it used マカロニ&チーズ. Google Translate is so weird. I don't trust it Also when I typed the first one in, it used 一番好き食べ物 but when I typed the second one in it said 私の好き食べ物
Sarcasm aside, tuna is my favorite food outside of very unremarkable food like 塩煎餅, 焼き飯, and 海苔. My answer generally falls under, "If it tastes good with or has 醤油 in it, I like it a lot."