So there are two different major kinds of submission, as I've figured. I call them "submission" vs. "subjugation" - that is, willing and accepting subs versus what're commonly called "bratty" or "smart-ass" subs. In both cases the sub willingly submits, but in the first they don't struggle while in the second they like to challenge the Dom.
In my relationship with Master, I'm more of the first kind; I don't really resist when Master ties me up or anything like that - I can't bring myself to! On the other hand, when I'm looking at BDSM erotica, I prefer to see some element of struggle or conflict; it's more visually compelling, I think.