Any of you guys watched dramas where it was the second lead that got your attention than the main, and deserved a drama centering him/her?

Cheese in the trap, InHo is one of my favorite characters ^^

and She was pretty, Siwon's character totally deserves his own drama ;p
Monstar - Kang Ha Neul drew my attention.
The Heirs hands down,my poor Young Do-.-
Prince of Lan Ling -Yuwen was everything
The dramas where I thought the Second Lead was better:

Battle of Changsha
Beethoven Virus
Chicago Typewriter
I Hear Your Voice
Love Rain
Pinocchio
Sassy Go Go
Scholar Who Walks The Night
The Heirs
The Master's Sun
Valid Love

but I've only had Second Lead Syndrome once...can you guess?

Warrior Baek Dong Soo - Dong Soo was boring.  Yeo Woon was less so, but the drama itself got so boring that it hardly mattered.  Lost potential all around.
King of Baking, Kim Tak Goo - Yeah, Tak Gu was boring too, and annoyingly plucky on top of that.  Ma Jun was relatable, if angsty.
Time Between Dog and Wolf - second lead was just way more likeable for me. 
Although I'm not sure any of those really needed a drama based on them, haha.  WBDS could have been written from the other perspective, though.
It wasn't SLS anymore in Cheese in the Trap, it's just that In Ho was a better character than Yoo Jung, but the drama/webtoon is about Yoo Jung's troubled personality so it can't be helped that he is the main lead.

Harry in I Miss You, it would have been a better drama if it was told based on his point of view. Jung Woo is a coward and childish. It's plain annoying.
Cheese in the Trap! I don't know if it was because of the contract conflict they had with the Park H, or that I just liked Seo Kang Joon's character more, but that is one of the first dramas that I wish they had filmed an alternate ending.

I almost had SLS for the drama Substitute Princess but because of the overwhelming response of the viewers the story line was actually changed so that the lead ended up with the original second lead. The drama was kind of a mess but it was still interesting.

Does 49Days count too??
Empress Ki - I hate the person she choose and I loved the one she rejected

Goddess of Fire - I never had such an awful second lead syndrom!

-> I dropped both of them because I couldn't accept her decision. Yes sometimes I am to emotional when it comes to dramas ^^

Sungkyunkwan Scandal - I like every other male role more than him
Bel Ami
Cheese in the trap
Who are you: School 2015 has one of the greatest second lead syndromes. Not that main male lead was bad but Yook Sungjae performed better than show producers expected which resulted to interesting character in drama and big SLS for everyone watching :D

Who Are You: School 2015
The Heirs
Goong
Warrior Baek Dong Soo
Chicago Typewriter
King of Baking, Kim Tak Goo
Pinocchio
Sassy Go Go
She Was Pretty
Sungkyunkwan Scandal
To The Beautiful You
My Lovely Girl
Cheese in the Trap
49 Days (?)
Reply 1988 (?)