Best in vanilla is Ebony or Glass, certainly, though Forsworn weapons look neat. Ebony Sword is probably my single favourite weapon in terms of design, but I always have access to Daedric by the time I can get one and go for the additional power...

Worst? Falmer. Looks lame. I like their armour though.

For the record, I really like the design of the iron weapons. I'd like it more if you could imprint it with runes somehow. I think it'd have been a neat early quest to have some way to craft a single "legendary" sword of your own with unique slightly overleveled enchantments using runes. You level up so fast in the beginning it'd only be overpowered for an hour tops, but would give you a weapon with a really personal touch that you could upgrade throughout the game.

On that note, make advanced armours or something increase the improvement rate of iron and other armours and weapons.

I'm a big fan of all the iron and steel weapons, simply because of how bland and awesome they look.
The ebony war axe and battleaxes look epic as hell too.
My favourites of the mentioned would have to be the steel sword, steel greatsword and ebony war axe.
Oh and let's not forget the Imperial bow.
And yes, the ebony bow is wonderful.

As for armor I love steel plate, steel nordic gauntlets and boots, dragonbone and also fur. Too bad I play on PS3. If I played on PC I could probably somehow mod the fur armor to be stronger. Wish I could use that stuff on higher levels without getting owned.

Chillrend. My favourite weapons are glass and daedric.