Both are based on highly rated visual novels where the protagonist suddenly gets dragged in many mysteries while surrounded by beautiful women. Furthermore these anime are very similar because of time travel (explaining more would be spoilers)
Also based on a visual novel that explores the "routes"/stories of three different cute girls. Takes place in the summer with beach scenes. Gorgeous animation. Also deals with reincarnation.
Air is a million times better - you will actually like the characters and feel invested in the story.