Even the FX top of the line eight core overclocked only compared to a mid range i5.
Its more of a matter of application as the eight core line is only comparable to an i5, but if gaming the i7 is basically an i5, but its when u get into the threaded applications that'll utilize an i7s HT that the i7s pull ahead
Gaming aside, the A10-5800k is comparable to Intel's older Core 2 Quad Q9650. The benchmarks in the following link basically shows that they are running neck to neck. There are no comparable game benchmarks due to the time gap when those CPU / APU were released; Q3 2008 vs Q3 2012.
Generally speaking, the amount of RAM does not really matter unless the programs you use are memory hogs. For example, working with very high resolutions in Photoshop (above 1920x1200) can take advantage of more than 4GB of RAM, especially if you have multiple Photoshop images open.
Click the following link for a comparison between the A10-5800k and i5-3570k.
AMD APUs are more so on level with the Core i3 family, so, considering that the Core i5 is above Core i3 in performance, the i5 is more powerful than the AMD A10.
In what case is it better? My knowledge tells me that the AMD excels in certain areas such as gaming and DAW's.
I get my knowledge from using a DAW. When it comes to Intel i5 Dual vs AMD APU Quad, the APU smokes the i5 because the DAW likes the 2 extra physical cores. Also, keep in mind that the APU series are way underclocked to save energy. My AMD A6 underclocked was at %50 CPU usage when running my DAW. Using the proper software..... i unlocked it to bump it up to 2.2ghz per core. CPU usage is barely %5. In this state the i5 would probably be in the %25 usage and if i needed more it would turbo boost..(overclock). My AMD A6 can go to 2.4ghz before even being considered overclocked. Most bench test on the AMD APU line are tested with it being stocked underclocked...in which is not a fair test comparing it to a Intel i Series.
Also, we excel the need of any dual core or quad core. Who care if Intel is faster or not. Its still over kill on both ends for any software task. Audio rendering is probably the most core tasking out of all software demands. Even the older Intel Xeon are holding their own with out breaking a sweat with DAWS.
We are only in "overkill" zone now with CPU's and we will not need that much horsepower for awhile.