What to look for in boots

Hey folks, I am in the market for a new pair of work boots and I'd like to better understand what to look for.

I have a pair of stock Belleville army boots I got at Benning about 15 years ago and I noticed that if i walk around in those boots all day I have a lot more energy and get a lot more done. Similarly I have a new pair of sketchers hiking shoes that just drain the life out of me after a couple of hours. They feel comfortable, but I just can't figure out what's wrong, i even tried some custom dr Scholls inserts (their machine scanned my feet and recommended cf420), but it didn't help.

Any idea what i should look for in a new pair of boots so they are similar comfort to Belleville?

TIA