As a retired masonry expert and great fan of Tamiya paint, I can tell you that there isn't one—there are many, and you should use at least a few.
Most bricks, especially older bricks, are not uniform in color if you look carefully. Depending on the appearance you want, various mixes of brown, red, yellow, and buff will work. Small amounts of green or blue should be added to buff, yellows should be dirty, red-browns need a touch of purple. Yellow "common" bricks should be very nonuniform in color, both between and within individual bricks.
Glazed brick and tile should be very uniform in color and very glossy.
Old mortar joints (pre 1920) are usually very white because
most of the mortars were hydrated lime—they contained no portland cement. After that date, mortar joints are more often slightly gray to very gray.
If you have any more specific questions, I'll be glad to help.