No such thing as light gathering. It can't be sucked in. However, bigger objectives and better lens rating are helpful in low light. Just remember, the light transmission rating is for a single lens. There are multiple lenses stacked in every scope. This is industry standard rating technique.
As example, a rating of 94% is at 1 lens, and total percentage of light transmitted to your eye drops with each additional lens in the body....so 94% rating can be as low as 40-60% at your eye. But it looks clear and bright cause it's magnified size and more sharply focused than your eye can be unaided .
Non optics technicians can effectively shop by price and name brand. And, ask around, which you are doing.
I've found the mid grade leupolds and Swarovski z3 (40-50 mm objectives , 1 in tubes) to be very fine low light hunters all in(mounted) under $1000
Similarity, I've found most all 36 mm and under objective scopes to be noticeably poorer low light performers regardless of brand/price.
Also, very helpful for low light is an uncluttered reticle with heavy to fine cross hairs. For low lite, skip all the dots, dashes, doodads, lines and numerals that come on the kiddy scopes.
Finally, for low light, keep it close to your eye so other ambient doesn't wash out your focus. This eliminates midbarrel optics (scout style) as serious low light contenders.
With the added caveat that any exit pupil over 7.1 to 6.0 ( depending on your age and eyes) really isn’t helpful. Where larger objectives matter is in seeing a wider FOV - therefore helping your brain interpret what it’s seeing… or meeting the max exit pupil at higher magnification. ( obj lense diameter/ magnification x light transmission % = exit pupil)
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