Howdy! Well, it is all personal taste....I have the "4 camera WIRED" system...
Here is one site:
Backup RV Systems - Tadibrothers
Rearview Systems: Backup Camera Safety Kits & Accessories
Have fun reading!
Personally, with perfect, 100% connectivity to the cameras is my PERSONAL ideal. That and I can keep my PHONE for it's purpose... also, the size of the 'available screen' sizes are far better than the PHONE option... but, if it 'works for you', GREAT!
Hope it all works great for you!