There's nowhere near the number of wizard series as there was for witches, and what there is, is extremely light-weight by comparison, but I do have boys who will ask for a chapter book about wizards. These are the three series that I suggest they choose from:
1. Woozy the Wizard by Elli Woodward. The three titles in this series are written in rhyming text and readers who can cope with the text, like Woozy, a confused old wizard who while meaning well does some very silly things.
2. Wizzbang Wizard by Scoular Anderson. There are only two books in this series. They tell readers the story of of Freddy Frogpurse who goes to visit his Great Uncle Sneezer to learn to become a wizard.
3. Oliver Moon by Sue Mongredien. This is the most popular of the series. There are twelve titles in this series and I have children who will read them all. Oliver Moon is the hardest working wizard at Magic School, but at home he has problems dealing with his unmagical parents.
The picture books about wizards are much better, (e.g. Little Wizard by Kazuno Kohara, The Princess and the Wizard by Julia Donaldson) but my good readers want chapter books and they really don't mind if they are formulaic or a bit 'twee'. The boys who are keen soon move onto Kate McMullan's Dragon Slayer's Academy and become engrossed in the adventures of Wiglaf.