A lot of games these days have some kind of affection system built into dialogue, allowing you to pursue relationships with characters you like, be a general prick to characters that you don't, and maybe even murder a few that REALLY antagonise you. Because sometimes it's better to let players decide for themselves which characters they like rather than saddle them with a party of people that they don't. Is this a feature that you enjoy and actively seek to manipulate for the desired outcome with a character you like/dislike, or something you tend to ignore? In your opinion, is this a good way of building character development and party interaction, or is this a poor substitute for good writing? Are there any games that you've played that you feel would benefit from some kind of affection system, and any that could have done without it?
Really varies on the implementation but I generally like those systems. Especially in Dragon Age games.
In certain games, this system can be a neat way of allowing the player to make the experience truly personal. Sims in particular centers around this function. As such, I will use it as an example of how I typically treat NPC's. I do not like doing anything to anger the vast majority of characters. However, I normally like to make an enemy out of one person in particular. Why do I do this? I like to experiment with all facets of a game while also pleasing as many characters as possible.
I haven't really played any games that use a feature like this (except maybe Fire Emblem) because it seems like these kinds of relationship systems are almost exclusively used for M rated games, which I don't play. I like the idea of these kinds of systems but I haven't really had an opportunity to play anything that uses one.