Well I could visualize 3 element here:
1. Bigger processor and RAM
2. Bigger battery capacity
3. Bigger Screen
These factors are important to let us experience better on our new phone.
Bigger Processor and RAM (Memory)
For me, this the most crucial for us the run multiple applications at the same time. If you a mobile gamers, this is even more important to run the 2k/4k display continously ( off course the Nvidia video processor is much better ). Running so many apps simultanously with lagging is the requirement to have such a bigger processor and RAM . Let say 2.4Ghz Octacore with 8gb RAM is the minimum requirement for todays smartphone?
Bigger battery capacity
Most of the smartphones come with range of 4000mAH to 4500mAH battery. Though it seems big enough , but it is actually not enough to run bigger processing on smartphone, like playing games, watching 4K/8K video, taking 4k/8K videos, or even video editing.
I would say the minimum battery requirement should be at least 5500 mAH. Then we would not have headache to find huge power bank capacity due to frequent battery drain on our smartphone.
I do believe today smartphone is not only for phone call or video calls or even video chat, but it is already beyond boundary. We now edit document with smartphone, video editing with smartphone, access cloud server via smartphone, and start to getting everything via smartphone. So, how is the screen we need to perform all this task? With 6 to 6.5 inch diagonal screen size, I would say it is balance between acceptably holding the smartphone and clearly working on the job assignment. bigger than that wont be called as smartphone anymore and smaller than that is quiet difficult to view the job on the screen
Well I do not opt for design but we still look into stylish smartphone rather than a bulky boxy one. But for me, the above two are the most important criteria.
This is very particular if you are a vlogger or photographer or those like to show off their new smart phone ( with superb design ). Bigger camera capacity could optimize your video and photo shot quality aspecially for traveller.
At the end, it is up to you what smartphone is your best choice, I could say most of the users buy expensive smartphone but utilize less than 50% of smatphone capacity. Is it a waste? well it is up to you again.