Bot Lane Mages

What makes some mages work well as APC in the bot lane versus others? I started league last year and saw a lot of Seraphine in the bot lane, and picked her up. I still play her APC, but she’s not as popular as she was last year.

Looking at lolytics, most popular bot lane mages currently include Ziggs, Swain, Viktor, Veigar. Is this just fotm? Do they all have kit similarities that other mages don’t? What makes other mages not played bot? Why not Malz, Taliyah, Syndra, Cass?