Late 2012 mac mini or late 2012 imac?

I recommend the Mac Mini as the i7 with hyper threading will do you much better for what your looking for. I assume gaming isn't a consideration, which would be the only reason I would get the iMac over the mini for its graphics card.

As for the fusion drive or the 1TB 5400rpm drive...def the fusion drive is the better of the two. Think of it as taking that 1TB hdd and adding a 128GB SSD too it, thats really all a fusion drive is...SSD Speed with added storage in one footprint, still leaves you the option to add a 2nd HDD if you need more in the future on the Mac Mini.

iMac really only adds a graphics card and IPS display. Also, to upgrade the RAM on a 2012 21.5" imac requires you to remove the screen and logic board...or pay an extra $200USD to double it to 16GB from the factory. Mac mini just requires a turning of a removable plate on the bottom. Get the Mini!

If you get the Mac Mini (which I think is better) then ONLY upgrade the processor - leave everything else stock. Then when it arrives you can upgrade all the RAM and the HDD to an SSD for a lot cheaper than Apples prices (and on the Mac Mini both of these operations are very easy to do).

Save yourself some money that way