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I would say: Most inquisitive:

Merriam-Webster:

1 : given to examination or investigation

2 : inclined to ask questions, especially : inordinately or improperly curious about the affairs of others

Cambridge Dictionary

wanting to discover as much as you can about things, sometimes in a way that annoys people

Someone who is inquisitive asks a lot of questions and is genuinely curious about things. They might take it a little too far, but it's a very weak negative connotation and one that doesn't really apply when you're in any context related to learning.

Particularly within academia, being inquisitive would be considered a badge of honor:

It's partly because humans are naturally inquisitive and exploratory but also, and more significant, because we need the unknown, what historians of religion call "otherness," to lend our lives significance.

— David Nicholson-Lord, Nation, 6 Oct. 1997

Inquisitive really only has a negative connotation when used to describe someone inquisitive about something that isn't their business, for example, inquisitive neighbors:

an inquisitive woman who tends to everybody's business but her own

And, while it shares a root with "inquisitor", "inquisitive" doesn't share any of that word's negative connotations.

I would recommend
Inquirer .

According to Cambridge Dictionary
(https://dictionary.cambridge.org/dictionary/english/inquirer?q=Inquirer+):

INQUIRER

​
someone
who asks about something

Synonym -
questioner

I would steal from the StackExchange platform. We give good question askers 3 badges:

• Curious


• Inquisitive


• Socratic

The last here being somewhat of a joke. Socrates is known as a philosopher for posing difficult "Socratic questions" to people.

As such, if you're intending this to be somewhat humorous, you could also use the term for your award and call it "Most Socratic":

Of or pertaining to, characteristic of, Socrates the Athenian philosopher, or his philosophy, methods, character, etc.

How about this:

Most curious ?

You could use "inquisitor".

a person making an inquiry, especially one seen to be excessively harsh or searching.

It does conjur up images (to me at least) of the Spanish Inquisition but if you are looking for a slightly tongue in cheek term it could fit the bill.

You might need to make up a word. Some words simply do not have straightforward translations. In German kindergarten names, they sometimes translate почемучка as Warumka ("why-ka") . But in that situation some of the context is quite obvious, e.g. that the word is meant to be cute and that it is some kind of non-native word.

You can try:

Best wonderer

A bit more whimsical, but a wonderer is someone who is curious about things.¹

_{1. ✔ocabulary.com}

As you've indicated a wish for a light-hearted gender neutral investitive (yes that's deliberately not investigative) noun I would propose

Questioneer n. (Much in the same vein as Buccaneer) but pronounced question-ear

Definition A person who benefits by asking pertinent questions that add to the greater good. (from KJO's Directory of malapropisms :-)

I'm going to suggest Grand Inquisitor:

Grand Inquisitor (Latin: Inquisitor Generalis, literally Inquisitor
General or General Inquisitor) was the lead official of the
Inquisition. The title usually refers to the chief inquisitor of the
Spanish Inquisition, even after the reunification of the inquisitions.
Secretaries-general of the Roman Inquisition were often styled as
Grand Inquisitor but the role and functions were different.

The title has also been used in a Dostoevsky poem, and in numerous Star Wars episodes, so it's well-known.

How about just Best questions?

While it is not term for the person, I think it would fit the other awards, as they all are about the end results: paper, presentation and poster, not the individual who made the contribution. It is also clearly positive, though it has more focus on the quality of the questions rather than amount of the questions. However, if this is not too serious award, I don't think that is too big of a problem, especially if it is questions in plural and not just best question. And on the other hand, I think you would not want to award somebody who just spams pointless questions.

Most obvious drawback is that it is neutral/serious rather than humorous.

You might consider

questionist

from the OED:

1. A (habitual or systematic) questioner, spec. in theological matters.
   Now rare.In early use applied to certain Scholastic philosophers, such
   as Aquinas and Duns Scotus.




2. At the universities of Cambridge and Harvard: an undergraduate in the
   last term before final examinations. Now hist.

This, I think, is now jocular, which may fit your purpose.

You could consider Best Poser

Punning on pose as in (from OED):

Raise (a question or matter for consideration) ‘the statement posed more questions than it answered’

And also poser as in (from OED):

A person who poses; a poseur.

Emphasising the potential attention-grabbing nature of questioning.

This depends on exactly the kind of light-hearted tone you're after though, and punning with non-native speakers can be a minefield you might want to avoid, especially with the slight negative connotations in the latter definition.