Leo & Jamal and Carojen are two of the most memorable out of the cast
I have to disagree with you here, if anything, as much as I love CaroJen, they're probably the second or third least memorable team in this cast.
Almost everyone will remember the Cowboys, Globes, and Margie & Luke due to having raced twice before, and Dave & Connor, Mark & Bopper, Twinnies and Afghanamals are definitely memorable, especially for teams that hadn't some sort of fan base prior to their first race.
Brenchal and Youtube are just well known, which automatically equals memorability.
Honestly the only team that I'd say are less memorable than the Country Singers are John & Jessica.
the Country Singers and just pray that this time around they give us a reason to remember them, and prove that the producers made the right decision when asking them to return!