This was a marketing point from years ago that from my understanding, has been proven wrong. Light tranmission is basically unaffected by main tube diameter, and it's mainly to make room the the electors for more adjustment.
So you got me doing a bunch of reading last night and now I've come to a bit of a light bulb moment...
Yes... you are correct with regard to light. It is very very minimal at best. I thought there was some slight image improvement. Basically it comes down to lenses used in that particular scope.
With regard to erector adjustment you are incorrect there only because some brands use the same erector assemblies in their 30 mm tubes as their 1" tubes. Also, some 1" tubes have more adjustment then 30 mm tubes.
With regard to 30 mm tubes being more durable than a 1" tube, that was proven to be a marketing scam as well. Most of the time a 1" tube fails it's because it's "old" construction versus new construction.
And... generally 1" tubes are supposed to be lighter, but that's not necessarily true.
So after doing a ton of reading... it's kind of funny... I always thought that a 30 mm was for image... I was wrong. I knew they weren't stronger because the tube wall thicknesses are basically the same.
So now... I have to agree with what another gentleman said.... look at what you desire in a scope.
Does it have to be ultra lightweight?
Do you need max adjustment for long range shooting?
Do you need a large objective to try and get as much light as possible for for first and last second of the day shooting?
Image clarity. Although that one is more a case of you pay for what you get.
Do you want a short scope for mounting on short action rifle?
Then lastly... what does your pocket book say it can afford? And don't ask the wife!!!!