darkSpyro

My personal least favorites are:

Magic: Don't have one yet (Spyro is my only magic skylander, and I think he's awsome)

Tech: Drobot- He's extremely powerful, don't get me wrong. But he's very boring to use. Drobot doesn't have alot of depth to him, all you do is just hold down the main attack button to shoot rapid-fire lasers (he's a bit more fun on clockwork dragon though). Not only that, but I personally think he's overpowered.

Earth: Bash- Same as Drobot, powerful but really boring and overpowered.

Life: Camo- Why does everyone like this one so much? I think he's severely overrated. When I first got him, he was extremely weak until I got the Melon GMO upgrade on Melon master. He's good in general, but I prefer the other Life Skylanders over him.

Water: Slam-Bam- Slow moving & short ranged, he's still awsome though. I also think his Soul Gem is kind of a stupid upgrade: Yeti Factor. Increased coolness and can surf faster. What does increased coolness do? The speed surfing is kinda useless for me.

Fire: Don't have one yet (Eruptor is my only fire skylander, but he's awsome like Spyro once you spend time with him; his soul gem is a retarded upgrade though).

Undead: Chop Chop- He's a little underrated in my opinion, but still porbably not the best Undead one. His attacks are too weak and he's a little too slow.

Air: Whirlwind- BO-RING! Her rainbows are kinda useless and her thunderclouds are the only good thing about her (and her ally-healing soul gem). I don't use her very often (except in co-op mode to heal my partner) and is without a doubt my least favorite skylander in my collection.

Magic: Wrecking Ball. Even though he's quite original, his cuteness which isn't even cute doesn't fit in. He is extremely boring to play, and very unusable. Least favorite overall.
Earth: Terrafail. He just bores me in general. Not very original, not very fun.
Water: Zap. I still like him a bit though.
Fire: Sunburn. Just because I don't enjoy his gameplay much.
Tech: Drobot. He is a cool character with a good idea but extremely boring to play which just kills him for me.
Undead: Hex. Just not very fond of her particularly due to her being Zook v -1.0.
Air: Sonic Boom. Though this was a tough choice because I really like all of Air!
Life: Stealth Elf. Boooring generic female elven stand-in who is way too overpowered.

I agree with most of your choices except for Terrafin, Zap, & Stealth Elf.

#1 Stealth Elf isn't overpowered, she's fast, got good combos, does alot of damage, and has a high critical hit; but she has very low armor, short-ranged attacks, her decoy is useless in battle mode (unless your opponent is an idiot or a newbie), and her soul gem is kinda useless (it takes a long time to heal her, plus it only gives you 5 health).

#2 I actually like Terrafin. Even though he's overpowered, he's still fun because of his uppercutting & bellyfloppping. He's pretty boring on the Sandhog path though. But at least he's got short-ranged moves, that weakens him in battle mode against long-ranged skylanders (except the Tech skylanders, not even Drobot could beat him). My only complaint is that he looks too much like a Street Shark, he used to look like a penguin with a shark's head, but they later changed his desgign, twice. Shoulda kept his 2nd concept art.

#3 Zap is the best Water one in my opinion. Fun and powerful, although he does have low armor and is utterly poor at close range.

Stealth Elf isn't overpowered, she's fast, got good combos, does alot of damage, and has a high critical hit;
Yep...

but she has very low armor,
Armor means almost nothing either way in Skylanders, though. Look at Dino-Rang, Earthen Avenger gives him a whopping +40, but nobody uses that path due to the other being simply better. Also, she can simply run away, she outspeeds literally everything.

short-ranged attacks,
No objections here, but she is designed for Melee, so logically she won't have many long Range attacks. There aren't very many characters that do both short and long range attacks well.

her decoy is useless in battle mode (unless your opponent is an idiot or a newbie),
No objections here.

and her soul gem is kinda useless (it takes a long time to heal her, plus it only gives you 5 health).
Again, she can run away, and hide.

In Battle she murders basically anything not called Ignitor or Zook and she might even be able to eek wins against them.

1. Nobody uses the Earthen Avenger path because of the Stonefist Trap Funeral Upgrade, it's useless unless there's a great big group of enemies. They say the Obsidian Armor is the only upgrade on that path worth purchasing. Besides everyone likes Prism Break's Crystaleer path and it's for his defensive capabilities.

2. Stealth Elf may be fast, but it's not very helpful against long-ranged fighters in battle mode.

3. She's short-ranged, which means she can only harm her opponent if he/she is nearby.

I will admit, Stealth Elf is a little overpowered in story mode, but not in gerneral or in battle mode.

Tashiji, please come in here

Quote: Nibelilt

Magic: Wrecking Ball. Even though he's quite original, his cuteness which isn't even cute doesn't fit in. He is extremely boring to play, and very unusable. Least favorite overall.
Earth: Bash. He just bores me in general, and is not very fun.
Water: Zap. I still like him a bit though.
Fire: Sunburn. Just because I don't enjoy his gameplay much.
Tech: Drobot. He is a cool character with a good idea but extremely boring to play which just kills him for me.
Undead: Hex. Just not very fond of her particularly due to her being Zook v -1.0.
Air: Lightning Rod. He's just my least favorite of the Air element
Life: Stealth Elf. Boooring generic female elven stand-in who is way too overpowered.

Most of these are mine so I just switched out a few