Any decent head unit will do the job. Pioneer, Sony, Alpine, JVC basically if you have heard of it then it should be OK.
The issue is speakers. Most head units put out about 40w which will be sufficient if you also fit a sub.
The standard front speakers are in just about the worst place, facing into the footwells.
Replace them with some reasonable mid range units and fit tweeters on the top of the dash.
Fitting rear speakers (where possible) makes a big difference as it fills out the sound, any half decent two way speaker will do as they only provide fill in sound.
What you must fit is a sub woofer, it can go in the battery box (but you’ll have to leave the lid off)
Or you can get one that fits in/on the back of the cubby box.
It doesn’t need to be the size of a suitcase, mine’s smaller than a shoe box and although it won’t win a “bass off” competition it produces good solid low end sound and with it turned on the system sounds good enough to surprise passengers.
