I'd like to thank Bart and everyone who have spent time posting and helping on this forum .... I started and stopped my research over a year ago as I was overwhelmed and discouraged. Now I'm back and have spent an insane amount of time researching what I'd like to build ...
Fortune favours the bold. Just jump in and buy a kit.
There have been many posts with lists of components that are compiled after much research and which are then changed following responses and advice from other members. Sometimes a multi-rotor gets built and sometimes another list of 'ideal' components is prepared. Everyone has their own way of doing things and my method was to jump in and buy a Mikrokopter Octo kit, not because that was going to be the perfect machine but because I knew everything I would need to get into the air would be included in the box.
I chose the Octo because it would at least be capable of carrying something bigger than a GoPro. It was only afterwards that I came across the expression 'redundancy', which refers to the flat 8 Octo's ability to stay airborne and controllable if a motor is lost. The MK Octo then obligingly displayed this facility when one of the cheap'n'nasty EP props broke in the air and it carried on as if nothing had happened. It then broke another, and another ... so I changed to APC props and it has not happened again.
The process of building it, configuring, testing and flying it and subsequently making small adjustments to various unfamiliar parameters through the initially totally unfamiliar interface of the MK Tool program gradually teaches you what it is all about - with help from this forum when you get stuck. Which Flight Control system or airframe or any of the other many variables is relatively immaterial at the beginning when you have absolutely no practical, hands-on experience of any of them and therefore have no reference points from which to judge their various merits or otherwise.
Practical experience of building, possibly repairing and understanding setup software will get you there far quicker than trying to work it all out in advance through forums and advice.
So, I advocate jumping in with both feet and buying a relatively inexpensive kit - not 'cheap', relatively inexpensive - to learn on. I am not an MK advocate, nor DJI or any of the others, but an MK kit is certainly a fairly reliable way to get started, as would be a DJI setup because the major components, i.e. airframe and flight control, are fairly well integrated and time-tested with many exponents here who can offer advice from personal experience.