The MoYou plates are great - the images are cut deeper than most plates so you usually get a really good transfer onto the nail.
I've got the small, Xl and rectangular stampers. I love the rectangular one as it is easier to get patterns lined up - but it is silicon and some of my polishes simply don't transfer to them - the metallics do! This and the xl stamper are great for long or wide nails - you can use them for smaller images but my thumbs are just too wide for most images. Here is a great link for sizes of images -
Oooh, Shinies!: Stamping Plate Sizes
Also it is good to have both a white and another colour - as you simply can't see if you have got a good transfer of white polish on a white stamper!
If you get a silicon stamper you really have to take care of it - don't use acetone free polish remover to clean it - I always use scotch tape to clean mine now - see this link -
4 ways to get an XL squishy stamper to work | messy mansion