Favorite Hold City e.g Riften, Whiterun
Mine would have to be Riften, great town (apart from the corruption)
Least favorite would be Windhelm. Just the environment puts me off a bit. And quite rude Nords.
2nd favorite would have to be Whiterun, normally the first Hold city you arrive in. It's people and it's environment are good- until the war and everything is wrecked. (I'm sure there is a Mod for that...)

Mine is Windhelm. I just like the people there, and its one of the cities I visit the most after going through dungeons since it has the most general merchants of any city. Getting to see Ulfric up close doesn't hurt either...

I like Windhelm and Whiterun. Don't care for Riften altho it does have a nice selection of merchants, even without TG connections. I hated Markarth at first but once I learned how to navigate the city I started liking it more.

My biggest gripe about major cities like Riften and Solitude is that you have to trek all the way out into the sticks to get to a smelter, unless you mod one into those locations somehow. Which I do, because I can, but I don't get the smelter until I buy a house in those cities so until I can manage that it's a real PITA.

Least favorite is probably Morthal. I'd rather go to Winterhold than Morthal... and that's saying something.

Riften.

Solitude, then Riften.

Dawnstar, probably - especially after kicking Skald The Elder back to whatever
hole in Talos-fanaticland he came from.

I'm disappointed, I came to Riften 1 era late. Riften back in the third and second era was a great place. The canol was great, no Thieves and Corruption and the Dawnguard. So now it is in disrepair and terrible. Still is my favourite house though, and merchants.
I then go to Whiterun, lovely location, nice people, best Jarl and housecarl. The house is a bit meh, with a mod though it adds an armoury and enchanting area where the alchemy lab was goes to stairs into a basemant.
Markarth is in mountains and I hate them, also I'm afraid of Dwemer things. Level 42 with no Automatons killed. I also like Solitude and Windhelm but I do not own either of them. Also Windhelm is full of racist Nords.
I would have to go with Whiterun hold but Honeyside house.

Not a fan of Windhelm either. Markarth I love. I always save it 'til last in a character's playthrough. http://images2.wikia.nocookie.net/__cb20110505071757/elderscrolls/images/f/f9/Markarth.jpg is the first screenshot of Skyrim I saw, so maybe that plays a part. Dwemer ruins, Orsimer Smiths, incognito Forsworn, lovestruck mages, there is so much going on there.

I really like Dawnstar, it’s a little out of the way but I really love it's location. It also fits my chactors persona.

Hard choice.
I like witherun, but Riften is closer to Home.

Design: Markarth
People: Whiterun
Feel: Windhelm
Shopping: Whiterun/Solitude
Location: Whiterun
Gameplay: Riften