The only variant I am worried about is the Brazil variant. It seems to have much greater humoral immune evasion and appears to be both more transmissible and more deadly (99% of the time, these occur together). Also, it’s understudied relative to other variants in relation to antigenic escape in vaccinated people, though the research I’ve seen indicates the Moderna and Pfizer vaccines should be effective against it.
On the bright side, we can produce new vaccines very quickly now, so I expect boosters for that variant to arrive if it becomes a large problem.
On the not-so-bright side, anti-vaxxers and anti-maskers will make it all go on longer than it should.