Eponine probably never went for Enjoras because he was even less interested in her than Marius was, lol. All revolution and justice for that boy; no time or interest in women. You can just see it in his exasperated face when the other boys are extolling the virtues of girls, lol.
Besides, Marius was different; not like the others. He came from a good upbringing and as much as he hid it, I'm sure it showed in his manners and actions. Eponine probably saw him and thought he could be her knight in shining armor.