For me it's information and how easy it is to access it. I've only been back in the hobby about 6 years after a long while away from it. Compared to now, I often wonder how the hell I got by back then. Books from the library or what the guys at the LFS told me were my main source of information. Now you've got more info, about any fish related subject you can think of, at the touch of a button.
Of course equipment's changed too but being a strong advocate of the KISS method of fishkeeping, Keep It Simple Stupid, I don't really go for fancy stuff, my set ups are pretty basic.
Welcome back to the hobby.