If you aren't going for the top of the line in processing speed, the AMD A-Series will generally get you more processing power for the money than the Intel equivalents.
If you can do with even less graphics power, similar to that of the intel Skylake processors, you could go with the AMD E-Series, but you would see performance loss in graphically intense desktop applications like web browsing and multimedia. If this is tolerable, then go ahead and save the extra money.
As of motherboards, it depends on what you want to do. So long as you don't want overclocking, any of the basic motherboards will do as the advanced voltage regulators really don't give an advantage on low-end processors unless you overclock. However, I'd recommend getting the better chipset if you want USB 3.0 and other features. If not you can go with the basic model.
As of RAM, for an economy machine you want 4GB to 8GB of RAM, and you probably should go ahead and dual-channel the ram if the motherboard supports it, because it will not cost much extra and almost double your RAM access speed.