I think maybe an IRIS as a first step to familiarise yourself with the flying of the things may be wise before looking at spending lots of money and/ or risking expensive photographic equipment.
You can always progress to a larger frame with bigger motors/ more lift later and cannibalise the iris for the control gear/ Pixhawk etc
Unless you are willing to part with insane amounts of money a larger quad (or probably better still would be a hex) in a ready to fly configuration is going to be out of the question therefore to keep the cost under control you will likely need to build it yourself from a kit of parts - Having at least some experience of flying is likely to be fairly essential to complete that task so again experience with the RTF IRIS is probably a good bet.
Just for interest, I am looking to start building a larger Hex using the Q800 frame kit shortly…
But in the mean time I am gaining flight experience with the IRIS.
Not had any experience of autonomous planes, flown plenty of normal RC ones though. Planes were way easier than RC helecopters when I flew them, but to be honest I would say the IRIS is way easier than a plane now. The advantage of a plane is they tend to give more flight time per battery or fuel tank but of course they never stop moving so not nearly so convenient for many photographic/ video uses, this video is a fairly good example of the advantage of a quad…