I’ve got the aldi cordless. Biggest problem is technique, don’t press too hard as you need to let it move. It was £30 as you can get spare lithium batteries direct from the helpline or the CPC one is the same (but red) and they sell the batteries cheap. In fact the cheap batteries is a very good reason to go for one of these ones as it means you can 1 or 2 spares ready.
I would like to try a mains one though. But the battery one comes in handy when doing a quick job or one outdoors. Excellent for cutting out precise holes in wood but it’s no angle grinder replacement. Just another tool that has it’s uses and speeds up fiddly jobs.