Curently, I kitted a Scout ASP to go mining a pristine metallic asteroid ring.
I play in a very relaxed fashion, with shields (so not a maximized cargo space).
I don't time it, but with a 40mn mining run, depending on my luck, I do between 1.5 and 2 million credits. Let's round it up to 3mil/hour.
I did more with bounty hunting (without PwP bonuses) in a hiRES when getting à good spawn but I love to try new roles and ships.
Trading was always the fastest way to net credits, with a safe round trip I could do 4mil/hour in my T6.
But really, credits come and go. I just do what I feel like to do, and enjoy that big galaxy of ours...