I recommend using Ravelrys pattern search filters to find crochet patterns that are for men to find patterns you like, then come to search here for the individual pattern names or designers.
Hexagon sweaters have been trending on social media lately. It is not something I would have thought for a man but with the right colour scheme it looks awesome.
I generally check the mens deisgn section of Drops designs. They have a large choice of cardigans, sweaters and such.
I personnally am quite fond of cable knit cardigans in men (and whatever about the sweater curse)
I believe that hats and beanies would be a safe choice. You could also make ones with patterns or different color variations. Making matching couple clothings would also be super adorable!