Syndra would be the most oppressive and strongest in regards to the current meta that you've listed for a laner. She can very easily 1-shot a squishy target with little effort if she is ahead, as well and providing reliable team-wide CC. She doesn't bring any escapes aside from throwing enemies away, and is prone to being targeted heavily by the enemy team to prevent her snowball.
Viktor is incredibly strong and brings similar burst potential to Syndra, however he is much harder to get the hang of and requires a certain "finesse" to be able to get to the point where you're strong enough to 1-combo other champions. He is a sort of dog-fighter, where he wants to get in with a massive chunk and back out to spam his lasers again until he's able to successfully guarantee a kill. He also lacks escapes, however he is one of the best wave pushers in the game.
Heimerdinger (the scientist Teemo guy you're thinking of) is one of most annoying champions for the enemy team to face. Your Turrets (Q) literally auto-farm for you while simultaneously harassing the enemy laner if they step into range, as well as protect you from ganks. As a jungle main, Heimerdinger is one of the lanes I will generally try my best to avoid, as I don't want to lose half my health from his turrets when I walk into lane only for him to walk away. You also pack a surprising punch with your W, and your Ultimate can be used in a wide variety of ways to be useful. He lacks escapes, but usually doesn't need them as he tends to run in a big circle around his turrets making life very annoying. He can safely be played Top against otherwise oppressive laners (such as Darius) to force them to sit in lane and hate their lives being unable to engage or roam without him taking your tower. Heimerdinger will always take your towers if you let him.
Lee Sin is very strong early game, but falls off VERY hard as the game progresses (aside from being able to kick a target into his team). He doesn't bring the same level of tankiness as, say, a Nautilus or Maokai, but lacks the raw numbers and dueling potential of a true assassins such as Kha'Zix. He's incredibly safe but reliant upon heavy mechanical input, so for a beginner I wouldn't recommend him. If you're able to predict where he wants to go and dodge his Q's, he's generally shut down very quickly.
Skarner is an outlier, he's super fun when you're ahead and basically forces the enemy ADC (or other squishies) to build a QSS or else he will drag them into his van (team). When he's behind, he's not very useful. A lot of his dueling potential comes from his Spires, and being able to make the most out of Q-spamming while stunning enemies with his E (granting the bonus from his Spires, temporarily). He has the same problems as Old Warwick did - he basically has to walk up and the opponent has to let it happen. His E is an incredibly slow-moving projectile that gets even slower after hitting a target, and he has to follow up with an auto attack for the stun to proc. This puts him in a more awkward spot, and basically makes him and walking Ultimate machine post-6. He scales fairly well as he has a %Health Shield on his W that grants Movement Speed as well as his Spires scaling incredibly well pushing his attack/movement speed through the roof, although his damage becomes sub-par compared to other other champions if he's not sitting on a Spire. If you build him damage, he lacks the tankiness to be able to walk up into the team and fight, but building him tank forces you to rely upon your team and be the frontline. He also has VERY bad mana problems if he's not on a Spire, he will be OOM (out of mana) after only a few seconds of dueling.
There's a bunch of other champions, but I'm not quite sure on what you'd enjoy the most. I tried to only list the champions you mentioned as liking, hope it helps!
