This analysis from last month found that, contrary to some peoples' intuition, Crossbow Expert + Sharpshooter is
not the optimal build for fighting in a cage match, despite its high DPR. Defensive Duelist proved to be superior for killing (simplified, spell-less) Slaads and Earth Elementals. Heavy Armor Master is also excellent in a variety of situations.
The real advantage of Sharpshooter is that it has a much wider niche than the average feat (applies to almost any combat, so it impacts almost a full third of the game); but it doesn't dominate other feats within their niche (many of which are also combat-oriented). It is not easy to determine which feat is the "best"; all that can be said with confidence is that there are a number of very attractive feats competing with each other.
Sorry for barging in like this, but since you keep bringing up that thred...
I didn't read the thread, since I thought it irrelevant to put a build largely dependant on range and mobility in a cage. Of course it can't come out ahead if you cut off its ability to switch targets, and its ability to (ahem) take advantage of advantage (presumably provided by somebody else), or its unsurpassed ability to focus fire on the "right" target every round.
To properly value the first part, you need to have an actual battlefield with several foes, somewhat spread out to mimic an actual combat scenario - any time the melee builds can't reach a new foe in time (and thus wastes an attack, i.e. automatically has its avg DPR set to zero for that attack), that heavily favors ranged builds. That, in turn, requires you to also put other ranged builds into the equation, so you can have them lose efficiency whenever you're "trapped" in melee with a foe (something the CE/SS build isn't susceptible to).
For the second part, you can assume "generic advantage" that just drops on a major monster (to simulate the actions of allies). Regardless, getting to shoot at monsters that are stunned, held or otherwise "at disadvantage" is a significant help in lowering the AC threshold to a point where -5/+10 really starts to pull away.
For the third part, you would need to compare various parties against each other (and not just one on one deathmatches), and specifically include at least one lineup where everybody in Team Heroes can project force at range (including our crossbow sharpshooter). This should lead you to a valuation of the team's ability to take out just the right target each round - perhaps the one about to pull a lever or otherwise needs to Die Right Now, or the one wounded and therefore the perfect candidate for Team Monster culling, or whatever. Do note that having two crossbow sharpshooters work beautifully together together, since they can tank too (by virtue of being Battlemaster Fighters), making a note of how this party composition doesn't mean you lose anything significant from your party's repertoire.
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But as I said, I haven't read the thread, so if those variables are taken into proper account, I instead laud you for it, and I shall have to read the thread to find out how Defensive Duelist still managed to came out ahead.
