I want purified water or filtered water for my tap in my kitchen sink?

I'm very confused on options. I do not want distilled water or reverse osmosis. Is there under counter types that don't require drilling a hole in my porcelin sink?I asked at Lowes and became more confused with all the options. I understand drilling a hole in porcelin is not a good idea and I think there are systems that don't require an additional faucet coming up through sink. I am also not interested in filtering the water through out my house. Just the kitchen faucet for better drinking water. Any help or suggestions would be greatly appreciated.