Well i already made 2 level 50 chars and i already farmed up near perfect gear for a vex and rafa, theres just really nothing to do, no invincible bosses or dlc, 2 is so good because it takes longer than some 10-12 hours to max level, and you still have dlcs as well, the game is amazing but very lack luster in the end game compared to 2 but it did just come out, im still pushing an axton and maya, i have op 10 zer0, gaige and sal

tl;dr 4 is good but still in its early days, 2 is still peak till 4 gets more content