If it’s free-splitting wood, like ash, a 4 tonne electric one will be OK. If it’s knotty then it’ll struggle. Check the shape of the splitting wedge as well. As a general rule high power machines with a wide wedge are best as smaller tend to use use a thin wedge which have a nasty habit of getting the log stuck on (same logic as a spitting maul vs a felling axe). If you have a chainsaw to deal with the knotty bits then a smallish electric one will deal with most of your splitting.
Electric ones tend to have a twin-button start to stop accidental operation. If you are doing lots, this can be back breaking as you’re forever bending over loading/unloading the logs and starting/holding the buttons. Vertical spitters are much better in this respect but are major money….. Best solution I’ve found is a hydraulic tractor mounted splitter, 4ft lengths at a time and all the power you need 😉
Edit – I drifted slightly – in conclusion a maul will be quicker….