My favorite so far is the Spriggan Earth Mother because I am currently mainly an archer and they provide a challenge for me every time I encounter one. I also like trolls, they provide a challenge at times too.

So what is yours?

Dragon Priests. They're evasive and hard to hit, while dishing out lots of damage themselves.

Ahh yes. I've heard quite a bit about the Dragon Priest being a challenge. Haven't gotten to fight one yet but I'm looking forward to it.

Dragon priests cause I like to collect their masks

I like the named undead boss fights in radiant quests, like the Warlord Garrick (spl). I enjoy them because, them being radiant, I never really know what I'm going to be facing when I get there. Sometimes they are just overgrown pvssycats, and sometimes they are unholy terrors to face, and there's no way to tell which until the fight is on.

Falmer Warmongers. They give good fights.

Any Skeever we can shoot with a powerful bow from a safe distance in sneak

Seriously, it's a tricky question. It's so dynamic, it all depends on our level. At low levels, wolf hunting with a bow is fun. Mid game probably Dragon hunting, but trying to run to a distant circling Dragon before it gets bored is sometimes frustrating. Late game, Gotta be Deathlords.....We love the bone crunching sound of burying a mace into a DL face

Dragons, on 360 with the way I play, were never an easy proposition. Now with Deadly Dragons installed on my PC, they are the creature of abject terror that they always should have been.

What level do Dragon Priest start appearing at?

If I had to pick one across all characters, it still would have to be dragons. They're not necessarily the toughest or trickiest things out there, but there's something very satisfying about battling this immense force of nature that can spit the very elements at you from a distance or bite your head off if you get too close. Not to mention the gawkers who gather around when you absorb the dragon's soul...

Named Dragon Priests are there from level 1, I think. Regualr Dragon Priests start showing up as Draugr bosses around level 50, maybe?

Lvl 1...if you delve into the dungeon or world space that they are in.... Not that I would recommend finding a Dragon Priest at lvl 1....but hey some people like impossible challenges.

When I'm in a mood to goof around, I head for a Giant. I find it endlessly entertaining to hit them with arrow after arrow while backing up. It's even more fun with a sword. I hit them once or twice, turn around, run and heal. Then I do it again. At a low level this can take awhile, but when I don't have the mental energy for roleplaying, it's just enough to occupy my brain cells for awhile.

I even made a mod that gives the Whiterun Giant extra health so that I can arrive there before he dies and don't have to endure another one of Aela's tongue-lashings for not helping out. That battle to wear him down can last anywhere from 15 to 20 minutes. The challenge here is to kill the Giant while not hitting the Companions fighting alongside you. This is trickier than it sounds. If you so much as scratch one of the Companions during the fight they turn on you the instant the Giant is dead. I think of it as my own home-made Giant-killing mini-game.

See below.

Heh. I do the same thing. I often create "fun" characters (using LaL to start them out in the world) and try to do something "impossible." I've managed to start a "left for dead" character in the hot springs, picked up the Atronach stone and some weapons, and then gone up and killed Krosis. Good mindless fun.

And undead. Don't feel guilty about 'killing' them.....

Anything with decent armour, weapons or loot that I can nick once I've killed it.

Rieklings. I like to play croquet with them in the wilds of Solstheim.

You know I've actually stopped collecting armor and weapons to sell now that I have a decent amount of gold and a reliable income selling other things. Best believe though if I go back broke or need some quick cash those will be the enemies I will be the most happy to fight

Hahaha I'm going to definitely have to do this

I'm with you - dragons.

My character is a no-melee mystic archer with low health, negligible armor and a magical specialty of illusion (useless vs dragons). If a dragon ever gets tooth/claw on her, she is dead. What she has going for her though are two big things: Tremendous skill with her bow and maxed resistance to magic. She can literally stand at range vs a dragon - trading arrows directly into his elemental damage shout - and prevail. Her challenge is, again, ensuring he never gets close enough to touch her. Altogether, dragon fighting with her is both satisfying and scary at the same time - therefore a favorite encounter.

Sometimes, for even more fun, she remains in the saddle of her precious mare and takes on the dragon using mounted archery. Great fun!

Another vote for dragons. I just love dragon fights. If they attack a settlement there’s the urgency of protecting the citizenry, and in the wilderness there’s different terrain and hostile wildlife to add to the fun.

I’m also a fan of the named dragon priests and draugr like Sigdis Gauldurson. I like that they’re in neat locations and different from one another.

Dragons are awesome. I first played skyrim when it came out years ago but then took a couple year vacation from it. Maybe I'm wrong but the dragon battles seem to be much more epic on the "legendary" version on skyrim then before. Maybe I remember it wrong but now they seem to be much harder to defeat and much more epic to fight than they did in the original unpached version.

Dragons, Dragon Priests, Trolls, Sabrecats and Spriggans.

Dragons, for their loot and souls.

Mine are Frost Trolls and Dragon Priests....I think it's hilarious when a Frost Troll hops up and down waving it's arms at me as I put an arrow through it...and that goofy UNNGHH as it takes the hit! The Priests just irritate me with their attitude...always love turning them into ash piles!

Funnily enough its currently deer/elk, they're very elusive so are a good test for a hunter, if you have a high enough sneak level you can sneak close enough behind them to slap them on the backside without them noticing you so long as you approach from behind, approach from teh front or sides and they will spot you and be off before you get a chance to get near (oddly enough without the Eye even opening, whats that about?) Currently busy hunting on Whiterun Plains.