Guild Wars 2

As it is, Daily Achievements have 4 set requirements.

My suggestion is to add to that, and scale the rewards depending on how many you complete.

For example:

4 Tasks – 3% EXP, 5s, Jug of Karma, Mystic Coin, Chance of additional Loot

6 Tasks – 4% EXP, 7s 50c, Jug of Karma, 2 Mystic Coins, Increased Chance of Additional Loot

8 Tasks – 5% EXP, 10s, 2 Jug of Karma, 3 Mystic Coins, Increased Chance of Additional Loot, Chance of [Bag of Crafting Materials] containing Rare Mats (ecto’s, lodestones ect)

10 Tasks – 6% EXP, 12s 50c, 2 Jugs of Karma, 5 Mystic Coins, Increased Chance of Additional Loot, Chance of [Bag of Crafting Materials] containing Rare Mats (ecto’s, lodestones ect)

12 Tasks – 7% EXP, 15s, 3 Jugs of Karma, 6 Mystic Coins, Increased Chance of Additional Loot, Chance of [Bag of Crafting Materials] containing Rare Mats (ecto’s, lodestones ect)

14 Tasks – 8% EXP, 17s 50c, 3 Jugs of Karma, 7 Mystic Coins, Increased Chance of Additional Loot, Chance of [Bag of Crafting Materials] containing Rare Mats (ecto’s, lodestones, T6 mats ect), Chance of [Bag of Fabled Items] containing materials for Legendary weapons (Obsidian Shards, Mystic Clovers, Crystals ect)

Possible Additional Tasks

Complete a Fractal
Complete a Story-Mode Dungeon
Complete an Explorable Mode Dungeon
Retake a Temple in Orr
Raise Fractal Difficulty by One
Do / Redo 1 / 3 / 5 Hearts
Do / Redo a JP
Earn 20 / 30 / 50 Influence for your Guild
Participate in a Meta Event
Kill 2 / 4 / 6 Veteran Mobs
Kill 1 / 2 / 3 Champions
Kill a Dragon
Free 1 / 3 / 5 Contested Waypoints
Gain 10 / 20 / 30 Achievement Points
Gather 1 / 3 / 5 Different Varieties of Ore
Gather 1 / 3 / 5 Different Varieties of Wood
Gather 1 / 3 / 5 Different Varieties of Plant