Hi, just wondering what your recommendations are for a character to do the main quests for all three expansions, ie race, class, skills, birthsign, etc. I'm not looking for the most powerful, just what you feel fits the quests best.

Thanks in advance

There's really not a best, because everyone experiences the game differently. I'd just go with what you feel suits you, and maybe try a few characters to see what fits.

as stated above,there isn′t really anything best as such.
depends on what you like.

magic users tends to go with either high elf or breton,or maybe dunmer since the latter has the hang of destruction.
fighters= using longswords,axes or blunt weapons is more suitable for orc′s,nord′s,imperials,or dunmer which have bonuses for longsword.
then you have thieves and such where bosmer and khajiit excels.
Bosmer or dark elf for archers would work.

for a bit of both,dunmer and imperials can be some sort of balanced characters that can be decent allrounders.
there is a character database here I belive in the pinned section,that could give some ideas.

My self usually goes for breton,no weakness as high elf′s has,and minor magicka bonus and bonuses for many magic schools,it requires some weapon training though since they have rather low skills from the beginning, if I go for a battlemage kind of character that is.

but there isn′t any best, all races and classes can be made into anything,some takes more effort than others obviously

Dunmers and Imperials are the generalists. You can do anything with them
Also there are specialized races- Bosmers (stealth) Nords (combat) and Bretons (magic) They aren't necessarily the most powerful in those classes but they don't have any weaknesses. Their attributes may leave something to be desired but costom making a class and/or choosing the right birth sign allows you to compensate for short attributes.
For instance, my second char is a Breton (modified) Scout. She's pretty good at whatever she does. The Combat and Stealth skills of the Scout are backed up by the natural spellcasting abilities of the Breton. But she is short on Strength, Endurance and Agility. Instead of a high magic birhtsign I give her the Lady and choose Strength and Agility for preferred attributes.
But this is only a suggestion,,,
Remember that the way to do whatever you want is Practice,Practice,Practice (and a little training doesn't hurt sometimes.)

It depends on your style. I like to play a combat oriented Nord. I usually put all of my major and minor skills in combat. Long Blade, spear, axe, handtohand (so I can fight with/without almost any weapon, I'm not a fan of ranged weapons tho). And then I get all 3 armor classes (its good to be able to wear a mix of everything, plus you level up faster as you level up 3 armor classes at once) and security (security is a good skill for any class as you will need to open locks for various quests, plus you can loot more chests). I sometimes use athletics and/or acrobatics on there too because I like to move around fast when in combat. I have beat all main quests with this setup and have beaten pretty much every powerful character (though if you level high enough with any character you can do almost anything no problem). Those are just my preferences its really no better or worse than anything else.

Thanks guys, I realise "best" is subjective, I probably could have worded my question better!

I've been playing for years, but have only completed the main quest and Tribunal a couple of times and never completed Bloodmoon. I suppose what I was really after was ideas for a character to take me through the main quests from a lore point of view, ie, what race would fit. I prefer to roleplay mages usually, so I think I might try a more combat orientated charcter.

The entire game is designed to acomodate virtualy any character build (the main quests especialy so because the game is built around them.) If your doing the MQ just make sure you have some skills for fighting. Other than that, do whatever you want.

Personaly I thing dunmer are the most lore-friendly race for the MQ. Then again it is specified that the Narevarine must be an outlander. That was Bethesda's way of making it "ok" to be any other race. But if you think about it Naravar was a chimer not a dunmer. Chimer were supposed to be almost identical (in appearance anyway) to altmer so that could be a possibility, especialy if you like mages.

(I'm pretty sure my lore is accurate, forgive me if I'm wrong)

Ash Vampires (Dagoth Ur's kin)) look a lot like Altmer IMO though not as tall. Probably they are (given what you're saying) Chimer as well.
Dagoth Ur's Gold mask could be designed to evoke this earlier kinship between the Velothi and the Altmer.

Just pick the race and class that appeals to you the most right now. The game works best playing as a character you want to use.

Well the general consensus is pure casters are the most difficult early on and stealth can be difficult for some people. In my opinion while combat isn't necessarily the easiest route, it is the most straightforward. I had the easiest playthrough of all campaigns with Thor, a Nord stock-class barbarian and it was a lot of fun especially at high levels when you move like an assassin but hit like a warrior.