I usually don't run a title. But right now I'm running Purified Devastator cause it just sounds cool.. lol

Master crafter, for the time it took.

On my main, I usually use thane of falkreath hold, because I remember the hour or so long struggle on the HM of Falkreath Hold final boss. Struggle where we nailed it bit by bit, we learned from every mistake and I actually spent a skillpoint for blood altar skill to help us beat it. (we were in there with 3 DDs and a tank) I sometimes use grand master crafter, like in the anniversary event when it was the PvP week and I wanted to signal every quester I was there not to kill, but to complete the quests.

I only use titles which suit their personality and/or what they're doing in the game, which means on most of my characters I don't use a title at all because they haven't unlocked one which suits them.

I don't worry about where the title comes from, partially because for most of them I don't remember where it comes from and partially because I never read them that way on other people's characters so it doesn't make sense to use them that way. For example if I see someone using 'Mageslayer' my assumption is that the specialise in countering magicka builds (PvP or otherwise), not that they've beaten whichever dungeon it is that actually gives the title.

I go with the one that best suits the character's story - Explorer, Savior of Nirn, Champion of Vivec, Grand Master Crafter or suchlike.

No title.

Every character has a surname, that's all I want and need

Master Angler and that probably won't change for a long time

I usually just go safe and use various stripper names on my toons