Now that I'm getting into gi-BJJ, I'm starting to pick up on a totally different style of submission fighting, so I gotta have two different lists.
Favorite submission: Flying Triangle Choke I've actually landed it in training a couple of times.
Best submission: Achilles Lock or Toeholds or Heel hooks It works.
Worst submission: Ten Finger Guillotine I've been trying to figure it out for like a year now and I still can't pull it off in sparring.
Favorite submission: Inside collar choke from guard My instructor was showing it to me as sort of an alternative to the guillotine for gi competitions.
Best submission: Cross body armbar I can hit it from pretty much any position, and it just keeps getting quicker and stronger.
Worst submission: Triangle choke I'm not really bad at it, but I've got short legs, so it's hard to pull tight.
Okay Ironman, I know this post is old as hell and it's probably from before I even joined, but I'm going to come right out and say it. You're an asshole lol. I remember one of the first real debates I got into on this forum (and one of the things that hooked me one coming back often) was a debate with you about Achilles locks. I remember defending that you could do real, significant damage with it (I.E. tearing ligaments, fracturing small bones etc) and you said it was nothing but a pain lock and no good BJJ practitioner should tap to it. Ahhh memories.
Anyways, on topic:
Favorite: This one is tough... but I have to go with nice, fast triangles. That or a reverse guillotine from N/S. I've been starting to like modified guillotines a lot lately too.
Best: A triangle in essence of any sort. Head/arm triangle, D'Arce chokes (they're modified head arm triangles :P), no arm triangles, you name it. I've loved triangles since I realized that you can essentially hit them from any position in some form or another and they can be very, very sneaky and very quick. This works with my style a lot as I throw a lot of "LOOK OUT!" submissions to keep my opponents guard up focused on other things while I set something else up (for example, trying for a kimura from side control and waiting for his arm to try and defend it over the top, then armbarring it). Also, the pure fluidity of the submission and the transitional ability of it is absolutely fantastic. I love chaining submissions together and the triangle is one of those submissions with a huge amount of potential moves out of it. From armbars, gogoplatas, omoplatas, Kimuras... TONS of em.
Worst: I'm not sure really... does gogoplata count? As far as worst basic submission, it's going to be kneebars. I can never seem to fully sink it in on people for some reason. I get their leg straight and their knee on my hip but it never seems to make them want to tap... maybe I should train with less flexible people? LOL