>>3194327>>3194329>>3194278Christ people google like this, "Camera_a vs Camera_B" whenever you ask this question. Thus, "D3100 vs D3400" you get:
http://cameradecision.com/compare/Nikon-D3100-vs-Nikon-D3400Personally, I choose the D3400. The D3400 has larger megapixels, more ISO range, longer battery life, etc. If cost is what you want to save then most of these things don't really matter.
http://cameradecision.com/compare/Nikon-D3100-vs-Nikon-D3300