some exchanges or crypto platform accepts direct Fiat deposit e.g binance exchange, KYC shouldn't be an issue if you have a clear mind, it's all for the sake of crypto world, some criminals are embezzling money with coins that's why KYC is important
If you want to use fiat on Binance via any method, be it credit card, bank transfer, direct deposit, etc., you will need to complete KYC. They might let you deposit first but then lock your account and freeze your money until after you perform KYC though.
Saying KYC isn't an issue if you aren't doing anything wrong is complete nonsense. This is just the "nothing to fear, nothing to hide" argument dressed up in a new skin. I am not doing anything illegal with bitcoin, but that doesn't mean I want a variety of complete strangers the world over being able to stick their noses in to my financial transactions whenever they like. I assume you aren't doing anything illegal online, but you don't share the passwords to your email addresses and social media accounts on here. The principle is exactly the same.
the top and best coins are Bitcoin and Ethereum, just do your own research, you can use coinmarketcap.com
Being a "top coin" on coinmarketcap means nothing as market cap is a meaningless statistic. Several of the top 10 coins are outright scams. You're safer just sticking to bitcoin.