I’ve had really mixed results over hte years - some really cheap ones have been great, some expensive ones have been crap!
I have a Bosch now, which is brilliant but still a bit ..erm .. not my favourite, although actually my in-laws have now got the newer version of same, and it seems to be more or less perfect :-)
Things to look for, best water/elec rating you can afford, half load/ or load sensing option so you can do a smaller load if necessary (lovely to finish the day/mad moment of cooking by being able to chuck everything in and switch on the machine even if it’s not full).
But,, honestly, i”d just start with the ratings. And special offers - I got my machine for about half price.
I also think that how well it works is often down to packing technique. I’ve got that down to a fine art over the years, and that has made the biggest difference (eg, make sure there is a decent space between every item, if things are spooned inside each other, they will not clean properly and you’ll have to do them again. It’s actually more sensible to clean sightless fewer items, and just do it once).
Not sure if that’s any help, whatsoever!