BannerBoo

Two things stood out, ease of use (for a complete novice, non-marketeer), and support.
I made a mess of activation, and was helped out so quickly that I upgraded a tier. And after a play around, found it really easy to use.
The only (minor) negative was that I used the AI generator a couple of times to see how well it worked without any serious intent to create anything, unaware that there are a set number of credits that quickly expire, so they were wasted for me - but probably partly my fault as I didn't properly read the details.