I find most people tiring to debate with, because they make it overly personal and come off as extremely unreasonable about their positions without much substance to back it up. It's not that I'm stubborn or unwilling to admit when I'm wrong, but that most people I encounter cannot come up with rational arguments that make their position worth seriously considering. And since I explore most angles before I am comfortable settling into a decision, it's most likely I've already considered their argument. If it failed to impress me the first time and they have nothing new and insightful to bring to the table, they're not going to get far.
Oh but ENTPs. They're the few that know how to appeal to my logical side, but also present new perspectives I might not have even realized existed. It's like viewing the world through a stereoscopic photo. It reveals a lot more depth than my own observations alone, but you need the two layers to make it complete. My ENTP girlfriend and I learn a lot from each other through constant discussion, and I've spent more time talking with her than everyone else combined. We usually have a lot of the same opinions, even if our approaches and methods aren't the same. It also helps that we have similar value systems, so there is no major conflict there. That's probably what makes our arrangement possible, because I cannot imagine either of us doing well with an individual that doesn't hold the same core values.
My one complaint, and we've worked on this, is that sometimes she gets a bit too passionate to the point it overwhelms me. Even when we agree. Sometimes she doesn't allow me enough processing time. Though I'm good at handling a lot at once, I still need to relate new information against what I already know to properly make sense of it. She gets extremely energized by a debate and suddenly she's off at full force, barely allowing me time to think and herself to breathe. It's probably an IE conflict? At first I didn't handle it well, because system overload makes me very frustrated and feeling harassed, so I'd cut her out and leave so I would have time to think things through on my own. And obviously she didn't take me leaving well and often felt like somehow she offended me, when it wasn't the case.
But I could never have a proper relationship with somebody that was not willing to tell me when I am wrong and why. Disagreements aren't necessarily unfriendly, as long as both parties are mature enough to handle it well.
-fests?
, and like Jen said, it's the energy/excitement over someone willing to meet us there, that we sometimes steam-roll forward, lest we lose the momentum, the moment, or the other changes their mind, train of thought. 
