Akaviri, ebony, ebonshadow (especially staves), glass (especially heavy) and dremora (detail alone makes this set 100% worth it and it looks badass).
Of the OG racial motifs, breton and imperial are my favourite. Breton has the best vanilla robes and the heavy is probably the closest you can get to making a crusader and i purchased the imperial upgrade just so i can get the imperial heavy armour because that's another awesome looking set.
Weapons: Pyandonean, They really are the best I have seen in terms of style, shape, size and the way they give the impression of solidity and good quality (without being clumsy).
Regular motifs: probably Bosmer and Redguard (legs, hands, feet) are the ones I use most.
Other motifs: Dead-water and Fang Lair Chests. Huntsman sash.
I also like Sunspire, when viewed at the outfit station, but I don't have it, obviously.
I don't like front/back flaps and hip things much, so anything that doesn't have them/minimises them and also suits my char tends to become a favourite.
Really, it's more a case of ruling out all the stuff I don't like.
But some quality ones are:
* glass
* ebony
* abah's watch light
* order of the hour
* trinimac light
* psijic
* pynadorean
* sun spire
In my opinion the light armor is very similar despite the fact there are so many motifs. The robe has the same length on all motifs except very few, it is the same dress which I find to repetitive. The flaps for light armor are pointless, since light armor players use a staff.
Also to many motifs are styled to look very menacing (again repetitive). I would like some motifs centered different themes, like healer, explorer, witch (soon to follow), various orders (like order of the hour or silver hand)
[PC/EU] Tamriel Hero, Stormproof, Grand Master Crafter
I love all the imperial-style motifs since I like the imperial cultural aesthetic, especially order of the hour. I also like elder argonian and deadwater