Which of the following methods do you prefer for leveling systems in games?
Level based method
The "traditional" method. Gaining XP as you go, killing things, completing quests and so on. Enemy creatures are fixed levels depending on area and don't level up when you do. Spawns are the same if you're level 1 or level 100, but previously difficult locations become gradually easier.
The Elder Scrolls method
When you level up, so do all the NPC's and enemies, and new spawns appear while others disappear as you continue to level up.
Cash for abilities
You use gold or XP to improve your stats, either focusing on some or spreading it out among more stats. Levels of enemies and NPC's stay the same.