assuming its for a DIY job only and not pro use, then a cheap one will do as long as you
a) calibrate it yourself, marking the deck and protractor with accurate measurements made with an angle finder on scrap wood
b) consider spending a bit of money on a nice blade. Finer TPI for a cleaner cut. The low TPI on most of the blads they come with is fine for smashing though stud work, but does tear out a bit.
Dont bother with anything fancy like a laser line etc.
230mm is a bit wide, so you’ll have to go for the more expensive sliding compound mitres saws if you want to do stuff in one pass.
9″ skirtings ? I’m impressed with the size of your skirting. Hire/borrow a sliding compound mitre saw. Or if you’re up for it, make yourself a very large mitre box – that’s what I would do for a one-of job.