hey jason
i have used affinity, it was OK ( sort of ) but there is no customer support so you kind of have to figure things out. PS has easy stuff like "save for web" affinity doesn't. PS has color channels, i couldn't figure that out on affinity. they have group / community based help board and some folks
are really knowledgeable, they also have a massive video ( 10 mins each so its not a huge investment of time ) library on vimeo ( i think? ) of how-to stuff. if i recall correctly, they have a 10 day free trial period so you can kick it around the block. my problem was i couldn't figure some stuff out, and my help-board-registration + question got "stuck in the pipe" so i wasn't able to get answers to my questions, and tried to get it sorted out by calling their mothership on the 1800# ... you know how sometimes customer service numbers are answered by people that shouldn't be anywhere near a customer service phone line. ... well a few years ago it was like this. maybe things are different now ? IDK...
for regular stuff like burn dodge levels, curves &c &c &c it seemed pretty good, and it was only $50..