Your faction zones story along with main quest

I would add the Fighters' Guild and Mages' Guild questlines here.

UESP's DLC table shows the same list as Trier_Sero's in a different way.

UESP's Prologe Quests page shows which prologue quest goes with which Chapter.

LootAllTheStuff wrote: »

Does completing the Mages and Fighters Guild quest lines have any impact on the final part of the main story quest? It's been a while since I ran through that, but my next character has just reached "Messages Across Tamriel" (AD version) without doing much of the Mage's one at all.

It does give a bit more story as to why they’re involved once you deal with Messages across Tamriel. It’s honestly best to get the guild quests done before Messages.

Also both (particularly the FG) are really important to the Solstice prologue and beyond.

You probably already know this, but just in case: You mention that you join all the guilds and factions for skill bars, but note that some, like scrying and some of the others, will not level unless you do their activities. The world opens up more if you do those things first. You gain access to digging up purple and gold antiquities for instance.
I think it's also worth doing the scribing quest-line, so you will gain access to the scripts that drop from certain dailies from the mages and fighters guild for instance.
When you do get to the dlc zones: I like picking up the zone dailies (for the dlc's) and do them if I'm close to the location anyway, or when I go questing in the specific location the dailies objective was. That way I get the rewards in a way that doesn't disrupt my exploring of the stories of the particular zone that I am in.

Also, the guild quest-lines are some of the best in my opinion, especially the thieves guild was fun and didn't just have good story-telling, but exciting quest objectives too. I am a sucker for doing things in the perfect order, but if you falter and don't enjoy the stories, maybe choose to do that questline before leaving eso for another game, it's probably worth it
I do not always enjoy the way the quests are set up with lots of generic fighting and fetching, but when I take my time and meet the people (not all interest me ofc) I often find many humorous characters and ones with truly heartfelt stories - and it's very enjoyable to roam such a world - good luck