From the many experimental effects the following caught my attention, I don't know how useful they are when we fight NPCs.
BEAM lasers: thermal shock, thermal vent (excellent, cools te ship for free and maybe makes it harder for NPCs to aim at you)
BURST lasers: Phasing sequence, scramble spectrum (BURST and PULSE)
Plasmas: Dispersal field (also in Cannons), plasma slug (also in railguns), Target lock breaker (PAs only) one of the best in the game?
Railguns: plasma slug (more damage than cannons), super penetrator (cannons come close)
Cannons: High yield shell, thermal cascade, dispersal field (also PA), force shell
If you're doing PvE which experimentals did you choose for your weapons?