Engagement is an occasion which is equally important and meaningful for men as it is for women. Because they too are eager and excited and anxious about the life that awaits for him and his would-be-wife after marriage soon after the engagement. So the gifts chosen for him should be also done with same care and effort for done for choosing gifts for women.
When a man decides to get engaged to a woman that means he is seriously in love with her and is ready to take responsibilities and settle down in life and has developed a serious attitude towards life. With engagement every man leaves behind his boyhood and enters into manhood. So the best gift for a man for his engagement can be a weeding planner book, a nice well tailored suit, a wrist watch. But to make it more personalized and special his close friends can gift him a documentary kind of thing in which his whole childhood to his manhood is shown nicely.
For any man a nice pair of cufflinks can be always useful. Even lessons for flights and scuba diving can be very different from the common and usual gifts.