How they compare
These are two different kinds of membership. Brazzers is one studio's network: big-name performers and glossy, high-budget scenes across many Brazzers sub-sites. Adult Time is closer to a porn streaming service, bundling content from dozens of studios, including VR, under one login.
On price, Adult Time is cheaper per month: $19.95 a month or $143.40 a year to stream at the time of writing, against $33.99 a month or $121.99 a year for Brazzers. Adult Time has a cheap short trial that converts to a higher monthly rate if you don't cancel.
Adult Time's variety is its point, though so much choice can feel unfocused. Brazzers is more consistent but can feel formulaic.