Hey, unfortunately I haven't been playing League for the past few months so I'm totally out of touch with the specifics of when/why to build certain items, particularly a new one like Hexoptics—I've built this probably less than 3 games in my life.

But just from the data + my intuition, considering it has both the best winrate and the lowest cost of all the viable first items to rush, I would say that you're probably right to think that it always feels good, because it likely is the best first item for almost any situation. Particularly since it even has a crazy good buildpath.

Kraken feels like it probably shouldn't have a niche anymore (outside of maybe very high Elo/ultra aggressive regions that want stronger early spikes) given that it relied on being the low-cost, good buildpath option while falling off, but Hexoptics fills that role now without falling off.

Stormrazor might be viable but likely seems straight up worse than Hexoptics.

That leaves only Yun Tal as the item I might potentially consider over Hexoptics for certain games since it should do noticeably far more DPS mid-late game, which both makes it a better scaling choice, but more importantly gives it a niche as the better anti-tank option.

So if I were you, over time I might experiment with both Hexoptics and Yun Tal in games vs ultra tanky comps and see how I anecdotally experience each of them in said scenarios. If I stick with Hexoptics over Yun Tal even vs very tanky comps, do I feel like I'm not lacking the DPS to deal with those targets? If I'm struggling against them with Hexoptics, does Yun Tal feel like a sufficient help to be worth the worse buildpath/earlygame?

Those are the only questions I feel you need to figure out in the current meta, because Hexoptics seems better than all the other items in every other scenario. So you just need to figure out whether Yun Tal being the better anti-tank choice makes it the better choice in certain games, or whether Hexoptics is so strong that it even crowds out Yun Tal in tank games.

If you just want to keep it simple and not over-think things; you definitely can't go wrong with rushing Hexoptics every game, that much is clear. Figuring out if Yun Tal has a place is just about potentially squeezing out a 5-10% better chance of winning in 10-20% of your games.

Glad you found the guide helpful!

As for Rapid Firecannon, it's both bad and great (but mostly bad). Firecannon is possibly the Zeal item that scales the absolute best of any Zeal item because of how heavily dependent the poke passive is on your current level of power in the game. A Firecannon poke auto can range from a tiny annoyance to the target enemy to a devastating chunk, both depending on your crit chance and your AD. The primary factor is crit chance (and crit amplification)—the more crit chance you have, the more likely your auto is to deal significantly more damage than a non-crit. AD is the secondary factor as your crits serve to amplify your AD, so the more AD you have, the more damage your crits will deal.

Lategame Firecannon is a great item on Jinx because it does synergize nicely with her range. The problem is that you don't typically build your Zeal item on Jinx lategame, you build it 2nd or 3rd item at the latest in almost all cases. Compared to the alternative choices of PD and Runaan's, Firecannon only obtains full value quite late into the game, but you're building your Zeal item now, and the game is statistically likely to end within the next 5-10 minutes. And right now, you get more value from the extra AS + MS of PD, and the extra AS + waveclear + AoE teamfight damage of Runaan's.

Right now in its current balance state, Firecannon is mostly just an item for ADCs who have even more synergy with it than Jinx, such as Jhin and Caitlyn—their fourth shot/headshot mechanics make it so their average Firecannon poke auto is far more damaging than Jinx's even at early stages, making that breakpoint of it being worth for them much quicker, so they can consider it from 2nd item onwards (depending on the build, in current meta builds it actually tends to be 3rd/4th item). Since Jinx lacks that poke amplification (rockets increase the poke by 10% which is something, but not enough to be significant), it just takes longer for Firecannon to be worth it for her.

So Firecannon for Jinx therefore ends up being either only a very niche item you build in highly unusual games (like facing 5 ranged champs, where the poke passive ends up being a disproprtionately high amount of your overall damage), or an optional item to swap in over PD/Runaan's in full build games where you have extra gold to optimize your build for the lategame stage you now find yourself in.

If it ever gets buffed (which it probably should be, I see no reason why it should be tied to only Jhin/Caitlyn right now, especially for as long as it has been), then you might be able to consider it sooner in a larger amount of games. But right now it's too weak to build in the majority of games, considering how long it takes to scale for Jinx and how soon you typically want your Zeal item.

Not a huge fan of it personally, but so long as you have Yun Tal it should be viable probably.

Haha, small world!

Good luck!