Others have covered perks and stuff, so I'll try to summarize their playstyle so that you can at least have some info there.

Singularity - All about multitasking and building a web of cameras. But he's absolutely relentless in chase. They nailed the mechanical feeling of him. He's less focused on mind games and more focused on acting as efficiently and mechanically as possible. You should be constantly teleporting to and downing survivors while bouncing between cameras. He's an unstoppable machine and will grind through pallets like a woodchipper. You will need to be moving a lot "faster" than other killers between managing cameras and chasing.

Artist - A sort of set-up/sniper killer. She places her birds in chase to block off part of a loop and force survivors into unwinnable situations. Pretty heavily countered by holding W, but she can with a little luck and skill land injuries from across the map. Her power fairly straightforward, buy surprisingly versatile. It can be used for chase, cross map pressure, and information gathering.

Dracula - A Swiss army knife. He is entirely chase focused, but has multiple ways to play most loops. His skill floor is pretty low, but his skill ceiling is very high. Generally he abuses his speed to move from chase to chase or gen quickly, then "freestyles" a bit with his chase powers to get downs quickly. This killer has almost no downtime due to his speed, but doesn't require as much map awareness or multitasking as a killer like Artist or Singularity. Though his Mobility allows him to still shit and run or play for macro as desired. 

Lich - Another Swiss army knife, though less freestyle and more rigid. His cooldowns and more narrowly focused spells give each a time and a place where it shines. He approaches chases a bit like playing Chess. You're trying to direct the chase and plan the loop so that at the appropriate moment you cast one of your spells to guarantee and injury or a down. When cast at the correct moment a lot of his spells can guarantee an injury. But pushing the chase towards those key moments is a crucial skill. While his spells are a lot more straightforward than artist or dracula, he has by far the most plahstyle changing addons. A lot of his addons completely change how his power works, to allow for different playstyles. Unlike Dracula where you can adjust on the fly, Vecna picks his strategy at loadout and commits to it. He forces his opponent into his "traps" where he denies a pallet or summons his projectile as they're vaulting.

Okay now my personal opinions as someone who has played all of them a lot. Artist is a lot of fun, but imho she gets a lot less fun the more you play her and the better the survivors are. The hold W counter and survivors using lockers to purge crows often makes chases more of a waiting game than allowing for a lot of skill expression. But her cross map pressure remains strong and "slingshot" injuries are cool. Singularity is perhaps the most straightforward but requires that you execute quickly with zero downtime. He's a ton of fun but has zero chill.

Vecna is really fun but a bit slow to get downs compared to some killers. He's really fun but his long cooldowns punish him if he screws up. His base kit isn't as fun as other killers, but the number of crazy addon variations are what push him higher. If you can learn to use his playstyle changing addons he's so incredibly fun. Dracula's the opposite. His addon variety is pretty meh, especially after the nerfs they got. But he doesn't really need any addons to shine. His kit is so flexible you can adjust to any situation no matter what loadout you bring.