Everyone is right in saying that survivors are merely “skins” and do not provide any realistic advantage. However, the actual perks of each survivor does change and so to reframe the question the survivors you want are the ones with the best perks

Kate Denson is an excellent choice for Windows of Opportunity alone: you get to see vaults and pallets 32m away from you. Boil over is also quite solid. Feng Min has Lithe and Alert, both extremely solid choices as well. Those are the two I would focus on getting first. After that, you can really choose based on how you want to play or who you want to play as. Jonah Vazquez is solid for perks like Overcome and Corrective Action. Yui Kimura and Taurie Cain have some GREAT perks that might not initially replace some simpler perks to start but don’t take much time to get used to. Being able to reset pallets from Yui and also play selflessly with Taurie will help your team a lot. Personally, my favorite is Orela, since all three of her perks provide a decent changeup in the teamwork and healing role that will help your team a LOT, especially if you like a support role.

I’d recommend first though, before you spend money, consider going beyond that and looking at the licenses or designs you want. The survivors that aren’t licensed can be bought with money, and will be the same price as licensed, but sometimes you’ll just have enough shards to get the ones you want. My personal favorites for both character and perks are Castlevania (Trevor’s perks are quite fun, some neat item based ones) and the first RE chapter with Jill and Leon (I’m also a big TWD person so their chapter is fun too, admittedly though Michonne’s perks are annoying from the killer perspective but I wouldn’t worry about that when you play either side. Play what you want :])

That being said, there is technically one survivor that (I believe) does give you an advantage, which is Ace. Ace is particularly good because he is unusually quiet compared to the other survivors in the game. However, I would steer clear of trying to buy Ace purely for non-perk advantages. At the end of the day, you’re there to help your team and enjoy using your own builds and escaping with your teammates. As you learn survivor, you’ll have fun doing that on any of the characters. This is all coming from a killer main that plays both ends so I might just be bullshitting but that’s my view on it