I like borderlands' loot system. In most fps games you have a close/mid/long range weapons and use the one you prefer, or in certain cases the only one that can work in certain maps/levels. You can easily play 80% of a game using the same weapon.

In borderlands I adapt my playstyle to the best weapon I currently have. For example, if I get an OP shotgun drop, then I'm gonna play more aggressively and seek close range fights more often than I normally would, which makes me change my playstyle a lot throughout one run. This combined with the variety of weapons makes it enjoyable for me, and I was never stuck because I lacked a good weapon to progress.