computerbroken :
Eximo :
Hmm, how much do you have to spend is a better way to look at it.
Absolute best cost/performance ratio is going to be a used desktop or laptop refurbished from some company. Newegg has an excellent search engine for that.
would desktop be 70% cost of a laptop or?
no limit, it's about best value
Best value would be to go to a thrift store and pick up whatever is still working?
For extreme portability a Windows tablet:
https://www.newegg.com/Product/Product.aspx?Item=N82E16834132158
Or this tiny ultrabook.
https://www.newegg.com/Product/Product.aspx?Item=9SIABYS5DM1716
Or for something slightly newer:
https://www.newegg.com/Product/Product.aspx?Item=N82E16834298866
All depends what you consider an acceptable expense. And keep in mind these machines were likely at someone's work desk running 9-5 every day for three to five years.
You could pick up the bargain laptop of the week at wal-mart or whatever. It will be terrible, but should meet all your requirements.
A desktop is cheaper in the regards that you get more performance for the money. But the base cost of a computer is pretty much the same. You can offset this a lot by already having peripherals (Monitor, Keyboard, Mouse, headphone/speakers)
Something like a refurbished all-in-one would be more portable, but really you might as well get a laptop at that point.
I might be tempted to recommend those refurbished machines to someone on a really tight budget. But if you didn't want to get a used system here are a few decent deals:
https://www.techbargains.com/category/359/computers/laptops
That $400 one isn't too bad for browsing and multimedia. Not a huge fan of spinning drives in ultrabooks, but you get what you pay for.