It depends on who the people are and what state of mind they're in when they meet. Instant "attraction" is on par with lust.
In order to truly know if you "like' or "love" someone you have to invest time getting to (know) them beyond their appearance and initial chemistry. It's not uncommon to see someone you think is "hot" but after spending a few minutes talking to them you realize they're not all that wonderful after all.
Being a man I would say it's rare for us to pursue dating women whom we find (unattractive) but are "nice" and "likeable".
I suspect a lot of women also would put men who had those traits into their "Friend Zone" as well.
It's our (sexual desire or romantic interest) in a person that separates "relationship love" from parental love, sibling, love, and friendship love. Physical attraction is usually the initial impetus for dating.