Over the years I've moved away from relays and adopted triacs for switching high voltage AC loads. Their quiet operation and compact size (heat sink excluded) are a plus. In the last few years, however, I've reverted to the electromechanical device. The prodigal son has returned (nahhh). Relays have their drawbacks including mechanical failure, contact point burning/pitting, and coil burnout, but they provide superb electrical isolation between control and power side of the circuit and negligible voltage drop across the contacts.
DC coil power input is via the 2-pin connector with red going to V+ as per convention, while relay contacts are accessed via the 3-way terminal block. I'm obsessed with isolation so I've placed them on opposite ends of the board.
The paper phenolic board is 1 x 3 inches, scored and snapped off from a 4x3-inch "mother" board which contains three other clones. Yeah, I'm mass producing this.... Uhhh sort of.