Multipurpose portable utility computing platforms are all well and good, but in a general sense are a jack of all trades and master of none.
I prefer to read on a kindle. I prefer to type on a laptop. I prefer to watch movies on an iPad. I carry my DS in case I want to game. I also carry a DSLR in case I feel like taking photos.
I can guarantee I get more work done on my laptop on the train than the guy with his iPad, and I take better photos than the guy with his phone out. I like to think I enjoy the gaming I do on the train more than the people playing bejewelled to pass time.
I've not weighed my bag, but it usually contains:
* 6D DSLR body, 20mm f/1.4, 35mm f/1.4 85mm f/1.4. (About 4KG total of lens & camera.)
* Xiaomi Notebook Air 13" (About 1.2 KG.)
* iPad Pro 9.7.
* Kobo H2O.
* Nintendo DS.
And other sundries: A couple moleskines and pens, a leatherman, headphones, a 20k mAh USB battery pack and lightning cable.