OP..if you have little experience riding various bikes then you can wax-philosophic on an infinite number of topics and likely end up with little progress toward where you'll actually end up, given some experience.
There's two types of people when they do research, or become tank commanders. 1) Aim, aim, aim, aim, aim. aim. aim, aim, aim, aim aim...fire!
or..
2) FIRE!, aim, Fire, aim, fire..
The second type gets where they're going much faster. There's no substitute for first-person experience.
Pick a bike(crusier, or hybrid, or drop bar road bike..bike shops rent them..start with an upright bike) and a 200 mile route. Make it easy..do a credit card tour...pack light.. take a few personal items and some clothes..and a credit card. Ride the route in 3, or 4, or 5(, or 6) days. If something didn't work or feel good/acceptable, then try something else or a different bike. Or skip the tour and just do successive, daily, day rides locally to cover the same distances in the same amount of time.
Two items pop up quickly with new riders:
1) With any type bike after a 20+ mile ride... "My butt hurts!" With time and/or the right saddle this goes away. Many people never get beyond this. This isn't a bad thing as this is where "like new" used bikes come from and the rest of us love to find these bikes.
2) With road (drop bar) bikes after a 20+ mile ride... "My neck hurts!" This comes from never riding a road bike and the rider being completely out of shape for this type of riding. With riding time and a proper front-end setup (stem length, degree rise..etc.) this goes away..or not and drop bars are not for you.
In both cases the "...with time goes away.." it takes more interest by the rider than a couple rides. People that are sincerely looking to get into and enjoy cycling get beyond both of these issues. Those with a "latest shiny object" approach to cycling provide used bikes for the rest of us.
You seem to favor an upright riding position. OK..go for it. It's the only way you'll find out if that position works for you. You're asking folks that have been through the bike/rider position "experiments" many years to many decades ago. Presumably they've settled into what works for them, based on first-person experience.
I can appreciate a good amount of analysis, but eventually one needs to bust a move. As a former(now retired) chemist(scientist/researcher) and data analyst...getting lost in analysis paralysis often, for some folks, generates many reasons not to even get started. Though the exercise in itself can be fun.