I prefer a single upfront purchase, though I am not against the idea of expansion packs or meaningful DLC (extra character races, maps, campaigns, etc). For online games, I think cosmetic DLCs are a good way to bank server costs. People who don't want to buy them aren't missing out on anything really, and the people who do get some nice swag/street cred to show off.

What I am completely against is pay-to-win crap.

In PvP, skilled players are at a disadvantage against prepubescent kids with daddy's credit card and that really ruins the experience.

The most ridiculous to me is when you can use real money to buy items/skills/exp for single-player games. I remember being shocked to see that there were several launch-day DLCs for Tales of Zestiria for packs of healing items or early weapons that are normally obtainable in-game, just to help you out in the beginning. There used to be cheat codes for this sort of thing, now the "cheat" is forking over cash.

Not only is it predatory, people are actually paying for something the game already gives them access to, essentially giving the publisher money for being able to play, and then giving them more money for being able to play less.