Before anything Id like to mention that this is only a good idea if its optional and doesnt result in the game becoming pay to win. Small advantages. Its also worth mentioning that this is only worthwhile if it will help fund/speed up development, because thats why most players would support this.
Im gonna spill some ideas here, you be the judge.
- Get a special look on your username indicating youre a subscriber.
- 5-10% luck across all drops as long as you are a subscriber (maybe less if its too much)
- even more reduced Fast travel prices
- every week/month get a small amount of marks of fortune, (ex 500 MoF per week)
- Make a VIP shop with exclusive skins, can only be bought with a special Subscription earned currency. These could be earned through either sub-only daily/weekly challenges, or they can be given weekly/monthly like MoF.
Any other ideas, feel free to leave em down there, this was just what I got right off the dome.