I just ran some numbers by hand (not as good as a software, but it is what it is) for levels between 5 and 11, using the fighter class.
Great Weapon Masters are DPR kings when AC is low or they have to hit bonuses outside the baseline (Bless, magic weapons, advantage, precision strike). Polearm Masters with a d10 weapon are always equal or better than TWF in DPR, and can get into crazy territory if they also take GWM. Plus, Polearm Masters get a number of other useful combat perks, and can easily afford to take defense style for an AC boost.
TWF wins the DPR race over sword & board with duelist style (only barely at level 11), but sword & board has more AC and an extra feat to spend for whatever they want (Shield Mastery, Sentinel, Resilient or perhaps a Con increase?).
I'm honestly comfortable in saying that TWF is currently the worse combat style in D&D 5e, for level 5+, outside of rogues and the odd build (I saw people mentioning paladins, possibly, and perhaps they're right).
I remain fully ready to change my mind if solid opposing evidence emerges.