Seungcheol: He'd be the type to be very gentle but rough at some points. He's the father of Seventeen, so he would know how to be pretty careful with his partner. Though at some points Seungcheol would lose a bit of willpower during it and end up kissing a bit more passionately, (unless they're into it as well. ;))) his partner would be his main interest to please and kiss more gently. He would be the more passionate kisser and somewhat insecure at times, so it'd be best if they showed him how much they enjoy him and his kisses.Jeonghan: Okay, so he's pretty and flirtatious. He knows it too. He doesn't really seem like the type to do rough kissing, so it's more likely small, teasing kisses that convey more of his feelings than the overly-heated ones. Also, he's a bit hand-sy with kissing as well. He would like slower, gentle kisses and not really care on how long they last, as long as his s/o knows how much he really loves and cares for them.
Joshua: This smoll is a gentleman. He, like all the other members, won't go past any boundaries that you set for them. With that said, he is more reserved with his kisses for his your sake. He would be a bit cautious with PDA until he became more comfortable and settled in the relationship. He relishes more into the small pecks and cuter nose kisses, but he wouldn't mind making out either.
Jun: He would be the passionate kisser as well. And like Seungcheol, he'd be a bit insecure which would make him put more effort into it, so they'd expect a few accidental bruises the first times he does it until he becomes more relaxed and reassured with their relationship. When he is confident and settled in the relationship, they'll be shown a pretty good kisser. He likes eskimo kisses in public just to fluster his s/o, fyi. :)
Hoshi: He is actually less needy with kisses (invests more on cuddling and hugging, sometimes intense cuddling). He's not really the insecure or reserved type, so he would kiss his s/o solely for the purpose of showing his affections or to do something weird in the middle of it to make them laugh. There will be moments where he needs more than just gentle ones and will become more affectionate and touchy-feely in the middle of it.
Wonwoo: Unless they are the first to initiate it with him, there is likely chance there won't be much kissing until later in the relationship. Wonwoo's a pretty reserved person in general, so he'd be nervous on how they react to him kissing them so suddenly. Once they bring him out of his shell, he'd be more assertive and at ease with kissing. He would be a softer kisser and more observant as to what his s/o likes, so they won't be disappointed whatsoever.
Woozi: Jihoon is also one of the members that are reserved. Though he is rough, he can easily tell what his s/o reacts to more and will try to fit to those needs. But he does have a lot of work to do, so he'd be one to indulge himself in the midst of it and do more passionate and heated make-out sessions. If they feel uncomfortable with that, then he'd probably force himself into cuddling and spooning them in apology.
DK: This is a ball of sunshine his s/o dealing with, it's mainly lots of fluff, I swear. He likes the cuter kisses and may want to prove himself in more intense ones; but overall, he'd like doing butterfly kisses, eskimo kisses, and smaller pecks. When he tries to prove himself and be intense with kissing, it'd be messy and awkward but still very cute. In the end of him trying, his s/o wouldn't be able to take him seriously and they'd end up laughing and embracing.
Mingyu: Mingyu is more clingy and likes kissing a lot. He needs PDA more than not and will literally hold onto you like a koala. His kisses are so sweet that they can be addictive to both him and his s/o. If they weren't into kissing before, likely chance they will be after him. He's a tower too, so he'll make sure to one day try to pick you up and kiss you or even do the cliché kiss-in-the-rain and the run-then-kiss.
The8: Ya'll think this kid is innocent. He could actually be one of the intense kissers, but I'm making this clean since he is young. He doesn't really do PDA since the members will tease him about it. His kisses are somewhat touchy-feely. He is very confident too, so he'll unintentionally be more assertive with it. If he pulls any kind of reaction from his s/o, they will feel the smug grin on his face. He likes longer kisses and will cling to you just for one at times.
Seungkwan: Diva Boo is not afraid of PDA honestly since he'll sass anyone and anything that holds him back. He isn't one for long kisses and like his s/o initiating the kisses rather than him. They won't know it, but he is going to be eternally screaming if they do any type of cutesy kiss, like a peck on the nose and such. To keep them away from realizing he's blushing slightly, he'll sass them to cover up his embarrassment.
Vernon: This kid thinks he can be smooth. Save him, The kisses he does will be repetitive and actually very soothing. He likes doing more soft and shy kisses, but he will try his hardest to show that he cares for them through these. He doesn't rely on kisses to show that he loves them since he shows them in other cute and flirty little actions, but he kisses a lot to make them feel happy, simply for amusement, and to be more secure with his s/o.
Dino: If his s/o initiates the kiss first, he'll need saving. Though he tries to act more mature with PDA, he is more likely to be shying away from it, especially since he is the maknae and will be teased mercilessly. He doesn't like to do long kisses since they seem messier and riskier to him. In the end, no matter what kind of kiss, how long the kiss lasted, or how hard he will try to keep his composure, he'll end up a bit of a flustered mess. He favours quick pecks, nose kisses, or cheek kisses overall.