In that case, even the cheapest PC on the market will serve those needs. Much of the expense of a computer is in it’s ability to render high resolution images/models quickly, a task that involves an ENORMOUS amount of number-crunching, and thus more powerful (and more expensive) hardware, with a little tacked on to ensure that it’s power supply can meet the power demands of the system.
Compared to gaming, the hardware required to watch YouTube or video chat, even in 1080HD, is relatively modest. Whatever computer you have now can do it. The phone I had 3–4 years ago could manage it. There’s $20 knock-off tablets in India that can do it. There is nothing in that task list that I see that couldn’t be done on even this little thing or this old refurbed relic.
Of course, running Windows on that low-spec hardware is dicey, and I don’t know how you feel about learning Linux… after installing it yourself, which may lead to tears if you lack confidence or choose the wrong distro. Not so much skill as you really only need to know your name, time zone, and what language you speak (presumably English) to install, but some still find it intimidating.
So basically, the only real criteria you have are cost, reliability, and pre-installed Windows because, no offense, I just don’t think you could handle a dramatic change like running Linux; while simple, it’s different enough from Windows in ways that I’m not sure you could adjust to without considerable external guidance. Windows requires a bit more powerful than many distros of Linux need, which drives up the price, but since we are so far below your $1,00 limit, we can afford to spend a few hundred more if we need to.
The only real complication there is that “reliability” covers not only how often it breaks, but also whether it will still work well enough 3–5 years from now; how future-proof it is. If your needs truly are what you listed in that post then the computer you have now will be plenty fine for at least another year or two, but if your needs change then so will your hardware requirements.
For that reason, something in a tower case is good as it has room for expansion as well as enough space to work in along with easy access through the side panel. Plus, most computer components are designed for ATX or compatible desktop cases. Some of your smaller computers require special power supplies, may not be able to fit a video card, or have some other restriction that makes buying parts for them trickier than just giving up a little space for a mid-tower (the most common sized computer there is).
With that in mind, I think a Lenovo K-series might not be bad. And despite my personal misgivings about Dell due to their Inspiron series and some past misdeeds, I would be remiss if I didn’t point out that their current generation of computers is well-regarded by many, and their XPS 8900 series seem powerful enough to remain relevant until at least 2020.