I've had the pleasure of being tied by Mistress Tran with rope, and for me there's nothing better.
I much prefer rope over some of the quicker, easier restraints because it adds a psychological element I really enjoy. First, tying takes a bit more time and effort. Rather than just slapping on some cuffs, there's something deeply erotic about a woman going through the effort of tying me, looping the rope and making sure all of the knots are right. It's just a little more intimate to me -- the bondage is a bit more personal and intentional. The other thing I like about it is that (in theory, although not when Mistress Tran ties you) with rope there is at least the possibility of escape. It just adds a little something to know that there's a reason to struggle, that if you weren't tied just right you might be able to wiggle free (or even better, to provoke your Mistress to add more ropes).
Because the psychological effect of tying is so significant to me, other than rope I like things that still involve tying: Stockings, scarves, etc. I find being tied with stockings to be a huge turn-on, especially in a scenario where it's spontaneous -- she takes her stockings off specifically to bind you with them. It has a certain intimacy to it, and a certain level of humiliation, that she can just use whatever she's wearing to bind and subdue you. Scarves have the same effect, but of course stockings are a bit more intimate of an item, so I prefer those.
Of course, for me a huge part of bondage is the gag (you're never more helpless than when you lose the power to speak and even beg for mercy), and I feel the same way about the gag -- nothing is hotter than being gagged by a woman with her panties (especially when she takes them off just to gag you with them). That's always a huge mind-fuck for me, to be unable to speak, made completely helpless by her most intimate of undergarments, forced to just lie there and taste my captor's most feminine tastes, constantly reminded of what I long for but blocked by the delicate fabric (and whatever other bonds are keeping me immobile) from sticking out my tongue to get taste heaven at its source.
Wow, I really need to get back for another visit to the Fortress....