It's worth noting that, when your question was closed, it was lacking a lot of detail. "Why was it closed" is not the same as "can it be reopened". I can't say for certain why your question was closed, as I was not one of the users that voted to close it. The listed close reason usually isn't too informative, so I'll recommend not focusing too much on the "too broad" part.
I can, however, offer a few observations that have kept me from voting to re-open the question as currently written, even with the substantial edits that have already been added:
It's not clear to me that there is a whole lot of question in it. There are three builds, with all class levels and most class specializations already chosen. It's not totally clear to me which variables still exist within each build. If there are few to no choices to make, then calculating maximum and average per-turn damage is a pretty straightforward computation, more suitable for a calculator than RPG.SE. That's not fatal to a question, but it strongly suggests that as part of your basic research effort (an expectation on all questions) you would present your own calculations for each.
It asks a somewhat oddly structured question. Optimization questions usually state a goal and some starting constraints, along the lines of
I'm creating a character that will have X levels in Rogue, choosing the Arcane Trickster specialization, and Two Weapon Fighting (Fighter or Ranger). With those constraints in mind, how can I build a character optimized for damage at level 20? I'm interested in both the highest single-attack damage and also the highest average reliable damage.
In contrast, this question includes three nearly complete builds (with respect to dealing damage), asks an optimization question for each of them implicitly, and then asks for a straightforward comparison of each of those. Additionally, because each of the builds has the same "base", it's unclear to me why they need to be considered at all. As above, a question asking about an optimized damage build with 15 levels of Rogue, taking the Arcane Trickster specialization, and Two Weapon Fighting (from Fighter or Ranger) seems like it would answer your question. Imposing the three builds seems to me like it distracts from what you are hoping to learn.
The question includes vague considerations that I don't understand in the context of writing an answer. The second build listed seeks "more versatility". If this is a damage optimization question, answerers will have trouble incorporating and understanding other factors unless you define some kind of hierarchy illustrating what tradeoffs you care about most. Similarly, from how the builds are written out I'm not clear on how those Attribute points were assigned, if there are ASIs available from advancing class levels, and so on.
So, in summary, the question is a little bit unclear about what constraints exist, what options exist, and what specific information you're seeking but don't already have. This is then tripled, for reasons which also seem a bit fuzzy. Those aren't necessarily enough to cause it to be closed, were it a fresh question, but that's not the situation we're in. These are reasons why I'm a bit hesitant to vote to reopen it myself, though other users may feel differently.
The other question:
Even if another question "should have been" closed as too broad, that doesn't mean anything with regard to your question. If they should both have been closed, the correct response would be to close the other one, not to open your own.
The other question contains a lot of detail about what the OP wants to achieve, in terms of both flavor and mechanics. It also lays out which class levels are required for the optimized build, and which are open for change. It includes priorities, and therefore tradeoffs, and a lot of detail about how the character is intended to be played.
It's also worth noting that that question was not that much better received than yours:
- They have roughly similar numbers of views
- They have received the same number of votes overall, though yours has
one more downvote
- The state of your question when it was closed was very, very
different from the other linked question's initial state. Your
question now is better than its first draft, but the initial close
reason will remain until it is reopened. "Initially too broad, now improved but not re-openable for a different reason" is not something that SE conveys to users very well