Learn English – Should I keep the second “than” in “A is better than B and than C”

Because I'm older than she, I should be the first chosen.

I loved her and then she died.

If it rains, then it pours.

I've had more than enough.

Would you rather be a mouse than a rat?

Who, other than you, likes the color red?

When there is a comparison, you use than; then means:

1. at that time; at the time in question: I was living in Cairo then | [after preposition] Phoebe by then was exhausted | [as adjective] a hotel where the then prime minister, Margaret Thatcher, was staying.
2. after that; next; afterward: she won the first and then the second game.
   • also; in addition: I'm paid a generous salary, and then there's the money I've made at the races.
3. in that case; therefore: if you do what I tell you, then there's nothing to worry about | well, that's okay then.
   • used at the end of a sentence to emphasize an inference being drawn: so you're still here, then.
   • used to finish off a conversation: see you in an hour, then.

(See also the definition of then given in the Oxford Living Dictionaries.)

The difference is qualitative versus quantitative. When you refer to higher quality, you say better and when you mean a bigger quantity, you say more.
In a casual use, when detail really doesn't matter, and you only mean one over another in a general sense, you may use either word in most contexts.

In the given context, prefer takes over instead:
"Many users prefer the look and feel of A over B."