Monarch have great prices??..er when..For the flights I have this year EZY from LPL are actually HALF the price of Monarch. Just to be sure I checked next years prices Man to Gib with them at nearly £350 for 2 (without pick your seats either) May/June time and almost double the price to Malaga where they have competition.
Most people I ever met on the LPL flights were deserters from Monarch due to cost.I note you live in Gib, maybe the flight prices are different from your end. I still stand by the BA remark, like Monarch they do have the odd good price day and date