Happiness.
As long as you’re not grossed out by zombies, Happiness hands down! It’s my favourite drama from him so far. Also the love story is beautiful and one of the best I’ve seen!

I liked him in High Society, but I have never finished the drama (and neither Suits).

Hwarang was bad but PHS was pretty good in this role.

Happiness was really good if you don't mind zombies.

He was cute in Heirs but his role was minimal.

I won't recommend Soundtrack#1, it looked great on paper but the result was pretty bad.

I love thrillers/zombies and I love a good friends-to-lovers so I think Happiness was made for me...I recommend it if you're ok with the zombie aspect! The Park Hyung Sik/Han Hyo Joo pairing is one of my favorites in kdramas.

Unlike most Beanies, I enjoyed Hwarang and especially him in it. Also Happiness but as everyone else notes, you gotta be ok w that zombie thing 😬

Park Hyun-shik and his eye acting. Sigh

Happiness.
What's Wrong With My Family? (Old weekender)
Juror 8 (movie)
High Society (just skip everything except for his scenes and Lee Ji Yi's).

I fell for him hard in Nine, and I always eagerly look forward to his work, because I know he can act, but honestly, he trims his eyebrows and hairline so much that his face looks like a china doll with no emotions. Nowadays I only like him if his role calls for messy hair that covers his forehead.

Happiness!

Granted I have only seen four PHS dramas (HWARANG, SWDBS, SUITS and HAPPINESS). I enjoyed them all and of those four I believe he gave his best performance in SUITS (2018). One of the things I am grateful to HWARANG for is introducing me to the Park brothers: Seo-joon (hyung) and Hyung-sik. I am eagerly awaiting PHS’s OUR BLOOMING YOUTH which as a US viewer I am pleased will be available on Viki US.

Suits.

100% worth watching Happiness for him, What's Wrong with My Family is also fun (I only watched the parts with Hyungshik though lol), and although the actual plot of Suits was boring, he's charming in the drama so depedning on how much you're willing to skip/forgive lol

*stretches fingers* My time has come! Honestly, anything with him is worth watching (even if ONLY for him sometimes), with Soundtrack being an unfortunate exception. I did not watch Nine, but people seem to love it and his performance, so add this one too if you're into retro time-travel dramas.

As everyone already said, Happiness currently is his best drama, and it's AWESOME. Best performance probably goes to Suits. So I'd recommend to choose one of the two, then watch his older works in whatever order you like and finish the journey with the remaining of that golden duo. That's how I did it after also starting from SWDBS and it was one of the greatest binge marathons in my kdrama experience ever. I did FF the hell out of Hwarang and High Society tho and basically just watched his parts. Didn't really miss anything, imo *evil grin* Oh, and he has abysmal part in Heirs that's utterly hilarious and is somewhere on YT as a short compilation with subs. Watch it if you need to laugh)))

Hiss less known works also worth trying: drama special Sirius (on YT with subs, he's playing teen leads in every episode's prologue) and Two Lights: Relumino (short ad movie, also on YT subbed). Won't take a lot of time too.

Also, boy is a really good singer (was main vocal in kpop group ZE:A). Their variety shows appearances, esp on Immortal Songs are fantastic - great performances, lots of funny (that one episode with sexy dance battle and his reactions lmao), totally recommend for broader understanding of how multi-talented he is. Generally speaking, all his variety shows are funny enough to give it a try. I'm still pissed that Real Men isn't subbed properly though... Overall, the more you see of him, the more you love him. It's that simple)))

What? No Strong Woman Do Bong Soon?? Happiness rocked too, as did Juror 8

Two Lights: Relumino and Suits. Two lights, his best look for me and this is a heartwarming short advertising movie... Suits for showing his acting skill and his natural look.
So far, his most successful project is still Strong Woman Do Bong Soon showing his comedic timing and talent.
While Happiness is popular in Intl fans, it has mixed reviews from knets, as episode 12 is a cop out for them.
His best performance is still in Sirius, that even he only had a small role, he showed his promising talent as a thespian. He can do melodrama here and I hope he will be given a chance to show his versatility in the future.
Looking forward to Our blooming youth, and it seems has a potential to be his best drama in his career.

Happiness hands down. I'm not into apocalyptic world genre neither into zombies, but this one is gem.

Specially his chemistry with Han Hayo Joo is on another level. Ultimate power couple Yi hyun - Sae bom.

he was swoonie in Strong woman KBS
and very mature and layered in Happiness. But I do realise Happiness is not for everyone because the other characters are sometimes hard to bare
I think PHS is pretty empathic towards his character, it´s almost even like he secretly wishes to break the frame and fight the unfairness of just being a character. he is trying to break them out of the screen.

I really liked Suits as well.
Also have to recommend In the Soop for reality tv, although he is there the shortest due to his schedule, but he has an interesting soft side with his friends.

1. Happiness (fantastic drama)
2. Juror (very good movie)
3. Two lights: relumino (drama special and the drama was great as well as phs)
4. Friendfication (variety only four episodes but good)
5. Suits (drama, but I watched the American show so this wasn’t up my alley although phd was awesome in it)
6. High society (drama; as everybody else pointed out - skim everything else other than his scenes, you’ll thank us later! Do not waste your time with any scene except for his scenes. I discovered him in this first and fell hard!)
7. and my last recomm - the greatest of all - his performance as well as the show itself were awesome and you already watched it - strong woman do bong soon!

I have many of these moments. He has very good chemistry with his female leads and is an easy watch (except in Hwarang where I personally felt Go Ara was wasted as the perpetually weeping wet blanket, but I digress).
I don’t have any new dramas to add, just wanted to say if you are watching to see Park Hyung Shik, Hwarang is worth it. But I’m also a big Park Seo Joon fan and the Park-Park Bromance ship was my dream ship. Heh. The drama wasn’t good but I’ve seen worse…there were some funny parts with all the flower boys. Much skipping required but then there are the shower scenes, ahem.
Happiness was a disappointment for me. I like zombie shows but the side characters in the apartment were SOOOOOO super annoying that there just wasn’t enough dying in it. Like I was waiting for the annoying characters to meet their well deserved ends. The chemistry between the leads was very good and I loved the FL character almost as much as I loved BongBong and his character in Happiness had such devotion and loyalty. And in passing, he looked great with some added weight imo and I hated how people were fat shaming all over. He looked grown up and manly as befit the character’s age and personality but I guess some want him to stay a cute little flower boy forever. He looks good both ways.
I will now go watch compilations on YouTube. Good luck with your PHS fix :)

I’m a couple weeks late, but stumbled on this post, and in case anyone is still checking it, as a big fan, I’ll share my recs, too!

1. Happiness
2. What Happens to My Family (53 eps but you’ll laugh and cry, it’s so good! Highly recommend.)
3. Two Lights Relumino (excellent short film on YouTube)
4. Soundtrack #1 (ignore the slander, this is a comfort watch!)
5. High Society but FF all the scenes without Changsoo & Jiyi
6. Suits (not bad, not great)
7. Hwarang (FF all the Go Ara scenes! Drama is trash but PHS was great)
8. Juror 8 (not bad, not good
9. Heirs (actually this is a fun, cheesy watch, not enough PHS to watch just for him, but there are fun moments and he’s great in it
10. Nine (he plays a kid, and he’s not in this too much, but it’s not a bad drama!)
11. Sirius- not worth checking out, really. Maybe YouTube some scenes of PHS and call it a day.