EDIT: I have received a lot of commentary on this, enough legitimate commentary that I decided to take a closer look at my answer. The results were mildly surprising to me. See below.
Either one has the right meaning and does not really carry bad connotations in my own intuition, although others have commented that questioner connotes an interrogation and that they much preferred asker.
I found this unusual, since questioner is by far the more common word in general English use:
A Google Ngram query for 'asker, questioner' reveals that 'questioner' is found overwhelmingly more often than 'asker'. In addition to the Google Ngram, a query against the BYU Corpus of Contemporary American English gives the following relative rankings:
WORD 1 (W1): ASKER (0.05)
WORD 2 (W2): QUESTIONER (19.53)
While the British National Corpus query gives:
WORD 1 (W1): ASKER (0.01) NONE
WORD 2 (W2): QUESTIONER (90.00)
At this point, I would've recommended you stick with questioner in most cases. And that answer was accepted, but it was not popular, and I wondered why. Dictionaries and thesauri did not show any evidence that either was more or less used, or had any particular connotation. I investigated whether it was a UK-US difference, but found no evidence of that either; the commenters did not have a geographic bias that I could discern.
Then I realized I had the perfect corpus right at hand: Stack Exchange itself! So I ran a search query against all SE sites. And to my surprise:
site:stackexchange.com asker
About 24,600 results
site:stackexchange.com questioner
About 3,260 results
And there you have it. In general English usage across all contexts, questioner is favored. But in Internet-based interactive context like that found on this -- a question and answer site -- asker is used more often by far.
Why is this so? I suspect that is because a query limited to StackExchange also limited the context to a more neutral or descriptive use. Alternatively, it may be that SE users come from a subset of the population -- generational? gender? education? -- that favors asker as more neutral.
Since you specifically say, "The context can be taken as referring to the people who ask questions on this site" then I must say that, contra my earlier thoughts, asker is the answer.
Vis-à-vis is a possibility. Literally, it means face to face, but it can also be used as an expression of comparison.
"Vis-à-vis our previous study, our results could not show the difference between A and B. The score for A was low, compared to their [its?] score." (Is the referent of "their" "our previous study"? I'm not sure.)
Other possibilities include
In relation to our previous study . . .
In terms of our previous study . . .
Comparing our previous study with our current study . . .
Putting the two studies side by side, we found that . . .
In a comparison between the former study and the current study, we found that . . .
Best Answer
I upvoted David's loaded question because it's a very common usage, but on reflection I realised that's not quite right for OP's context.
A loaded question is nearly always one that's asked in such a way as to force or encourage a particular answer (that the answerer might not give if the question were presented "fairly").
But a trick question is one where the questioner usually doesn't care what you answer - you'll be wrong no matter what you say. I don't normally cite Urban Dictionary, but here's their definition...
My favourite trick question is "Have you stopped beating your wife yet?", but David's "When polar bears eat penguins, do they get indigestion?" is neat too. But they're both slightly different to the example cited above (that has two wrong answers, ours don't really have "answers" at all).