I also have a 280x as well. It's a very high performing card and a good value. Since you said that you will be playing crysis 3 and BF4, then you probably should go for AMD since both of those titles are optimized for AMD. Also you will be able to take advantage of Mantle support to get better performance when the December update comes out for BF4. Not only that but you can take advantage of the extra 1gb of vram that the 280x has over the gtx 760.
Well I might add something you didn't know you can ask them via email to add components that are not listed on the site...
Nr.1 : CPU cooler - Cooler Master 212 EVO
Nr.2: Increase the HDD to a 2TB (trust me 1TB fills out quickly bru) R455 more
A few extra's:
(this is only for later) Samsung 840 EVO SSD (for faster boots, loading times, program launches ect) can be done at a much later time
PS add me on Battle log DUIW3L
Awesome guys thanks, I'll go for the 280X then Only problem with those few extras is that im on quite a tight budget, I have a CPU cooler the Cooler Master V6 that i can use in this pc hopefully, as for the SSD, i wish i could ^^, will try to get one next year though I'll add you as soon as i get my pc and BF4
Have you considered the MSI r9 280x? It's priced roughly the same(where I am the MSI is actually a little cheaper) and is clocked a little faster. Ignore the reviews about coil whine and overheating vrms. MSI fixed that with a bios update.