iPad Pro (Advanced Artists) $$
The 11" iPad Pro will more than meet most artists' needs. I used an older 10.5" iPad Pro (with 512GB of storage) professionally for many years before upgrading.
When investing in an iPad, my advice is to get the most storage your budget will allow.
To save a little on cost, refurbished iPads (purchased directly from Apple) are also a great option. I have purchased a refurbished iPad in the past and it still works well to this day.