夕飯は何がいい？
What would you like for dinner?
=What do you want to eat for dinner?
A: What would you like for dinner?
B: How about pizza?
A: 夕飯は何が食べたい？
B: ピザはどうかなあ？
★for dinnerで「夕食に」。例 have tempura for dinner「夕食にテンプラを食べる」/What did you eat[have] for breakfast?朝食に何を食べましたか?