I finally watched Teen Titans and really loved it. HQ challenged me to list my top 10/15 episodes and I came up with 14 figured I'd also share them here.
S01 E06 "Nevermore"
During a battle with Dr. Light, Raven loses control of her powers, which makes the Titans worried. Later, Beast Boy and Cyborg sneak into Raven’s room and Beast Boy discovers a strange-looking mirror, which sucks him and Cyborg into alternate realm where they meet different sides of Raven. Unbeknownst to them, they've stumbled upon a portal into Raven's mind, where extremely terrifying thoughts and threats are waiting for them deep within.
S01 E10 "Mad Mod"
Mysteriously ambushed and knocked out cold, the Titans wake to find themselves in the hands of Mad Mod who has decided that the Titans are misbehaving children who need to go back to school. He says he'll teach them a lesson they won't forget, a lesson which includes hypnosis, brainwashing, and dangerous school materials.
"Every Dog Has His Day" Being ignored by his busy teammates, Beast Boy feels lonely, so he wanders the town eventually turning into a green dog. To his surprise he crashes into another green dog that is being pursued by a flying saucer. The saucer picks Beast Boy up mistaking him for the real thing. On board the saucer, Beast Boy meets Soto, the dog's owner, an alien who acts all of two years old- and throws vicious tantrums aplenty. Beast Boy tries to makes his escape before Soto takes off for his home planet, but it's not as easy as he thought it would be. Meanwhile, the other Titans have noticed Beast Boy has gone missing, and end up chasing Soto's dog, believing it's their teammate.
"Date with Destiny" In order to protect the city from an army of moths, Robin has no choice but to agree to the villain Killer Moth's demand: to take his daughter, Kitten, to her prom, much to the chagrin of a very jealous Starfire- and Kitten's ex.
"Winner Take All" During a fierce card game in the Tower, Robin, Cyborg, and Beast Boy are zapped to another dimension, along with Speedy, Hot Spot, Gizmo, Aqualad, and Wildebeest. Here they meet the Master of Games, who announces that they are invited to a battle tournament to decide who is the greatest warrior of all time. Cyborg however soon starts to suspect the tournament of being more than what the Master of Games tells them.
"Aftershock" August 14, 2004 (Cartoon Network)
February 5, 2005 (Kids' WB!) 257–332 Terra returns- but now following under Slade with a totally uncharacteristic and horrifying desire for vengeance. The Titans must now stop three escaped criminals, and their former comrade turned enemy.
"Deception" The Titans send Cyborg undercover as Stone to investigate the HIVE's newest plan. Cyborg finds out that a new headmaster, Brother Blood, is now in charge of the academy, with a whole slew of nasty plots underway to unleash terror. Brother Blood, Gizmo, Jinx and Mammoth.
"X" The Titans investigate a break-in by an unknown intruder. Much to the group's surprise, the thief is Robin's (retired) criminal alter-ego, Red X. As the team scrambles to track him down, Robin broods on how the creation of Red X was a mistake, and resolves to fix it by bringing the new Red X down. Things take an unexpected turn when Professor Chang, a scientist and weapons dealer, captures the other Titans and prepares to unleash a doomsday weapon on the city, forcing a team-up between Robin and Red X to stop him. Can this unlikely alliance save the city?
"Haunted" Ever since Slade disappeared, Robin has been questioning whether or not Slade is really gone. However, when Cinderblock breaks out of jail, Robin begins seeing Slade again. However, the problem is that he is the only one who can. Has Slade actually returned, or is there something sinister messing with Robin's head?
"Revolution" October 16, 2004 (Cartoon Network) 257–487 It's the Fourth of July and everyone is celebrating, until Mad Mod crashes the party and uses his hypno-screens to hypnotize everyone into serving him as "King Moddy the First" and transforms the city's infrastructure into strange copies of British buildings, claiming that the United States now belong with Britain again. When the Titans go after him, he steals Robin's youth with his cane, turning the leader of the Teen Titans into a gray-haired and weak old man, and the rest of the team has to rescue him while facing down the belligerent Brit's army.
"Bunny Raven... or... How to Make A Titananimal Disappear" When trying to stop The Amazing Mumbo, the Titans are sucked into his hat and Raven is separated from the rest of the group. However, when they find her, they discover that Raven has been transformed into a rabbit. Soon after, Mumbo changes the rest of the Titans into animals: Robin, a monkey; Starfire, an orange and black striped cat; Cyborg, a bear wearing an endless number of tutus; and Beast Boy, a lamp (retaining his ability to shapeshift, but restricted to inanimate objects), after he learns turning him into an animal is pointless. The Titans must think of a way to defeat Mumbo, otherwise they will disappear forever after Mumbo's grand finale.
"Employee of the Month" Amidst a series of UFO raids on farms (with the targets being cows, to everyone's mystification), Beast Boy wants a moped but has no money to get one of his own. Robin won't buy him one and Cyborg won't build one, so the only way for him to get one is to get a job at Mega Meaty Meat, a restaurant which sells nothing but meat. Beast Boy manages to overcome his distaste for meat in order to get the job, but his workplace proves to be more than just a restaurant.
"Lightspeed" The Titans East are called back to Steel City and the HIVE Five takes advantage of their absence to steal and rob unhindered. But a new hero called Kid Flash suddenly appears and hampers them at several occasions; at the same time, however, he develops a strong crush on Jinx and makes an effort to convince her to abandon the Hive Five. When Madame Rouge arrives in the city to capture Kid Flash, Jinx finds herself questioning whether she really wants to join the Brotherhood of Evil.
"Revved Up" Ding Dong Daddy steals a briefcase from Robin, containing his most prized possession. The only way for him to get it back is to beat Ding Dong Daddy in a race. Red X and Gizmo discover this and Gizmo reveals this to a horde of villains who join the race. Red X disables the villains and Robin wins the race. It is never revealed what the briefcase contained.