I started skiing properly 25 years ago, have owned 5 pairs of skis in that time, and ski probably 12-20 days a year (although in some years I’ve skied much more, never less though.) I would not be without my own skis. I don’t own them to save money, I own them because I like having my own kit.
For me, it’s like this:
Own skis - I have to take care of them, am careful not to ski over rocks and smack them about.
Rental skis - other people have skied them over rocks and smacked them about.
I have all mountain skis - previous 2 sets were Salomons but when I came to change skis last year the Salomons were not getting good reviews for the decorative finished (upper surface was chipping easily) so I went for Nordic’s Santa Ana 88s and can honestly say they are the loveliest skis I’ve ever owned, both in terms of looks as well as performance. They are currently about 400-450 euros on sale with bindings.
It’s no bother getting skis serviced. Usually costs about 15-20 euros once every couple of years, between times DH and I service them ourselves. Plenty of YouTube videos on how to do this.
Wrt rental skis, if you know what you want exactly, you can often get good skis if you ask. But most renters (especially British) are seen as clueless novices when it comes to ski brands, models etc, even if they ski reasonably well (I say this from the pov of someone who has lived in a ski resort and DH worked in a ski shop) so generally tend to get given the bog standard rental skis which are not the best and often in pretty average condition. If you are lucky, and ask nicely, and know what you want, you can get some awesome skis - DS got brand new racing skis this year at first rental place. Later on, in different snow conditions, he picked up good but slightly knackered twin tips. It’s not good enough to know which specific brand and model you want though, you need to be able to say what type you want and know enough about skis to recognise if you are being given what you ask for, as shops will not have every ski on the planet available.
I would always prefer my own skis over rental skis though.