Towing mirrors - which ones?

New to this game so getting myself set up for car and caravan that I'm picking up later in the week.

Had a look online and couldn't believe how many different types of towing mirrors that one can choose from - but which ones are best?

I've seen the standard strap on ones and, although the cheapest, they don't seem to be the most sturdiest. The clamped type look more robust but have read some stories about marking the car wing mirrors and difficulty in adjusting. The Milenco ones look to be the most popular. 

I'm getting a Discovery Sport 2019 reg so just seeing if anyone can help with any advice before I just pop into Halfords and get some of theirs.