get better gpu or an apu?

[Dame la mochila]

my pc specs:
motherboard: ASRock FM2A55M-VG3+
processor: apu a4-4000
ram: 4 gb
gpu: geforce 9800 gt 1gb ddr3

my question is if i should buy a better apu (like a10) or get a better gpu (r7 360 2gb ddr5)?

what would be worther for playing games like cs:go in 60+ fps?
with my current pc i can get 50-60 fps in minimun video sets, but i get fps drops very often, it aint a smooth gameplay (like in train or dust more than others. well... always get fps drops, its not stable at all).
sorry for bad english

Update:
First of all thx for the answers guys.
I havent said that my budget is quiiiite limited, so i can afford either a better GPU, and staying with the APU as a normal CPU like how i was using it for the last time (cause at the first i hadnt a dedicated GPU, just the APU with its integrated, but when i got some money i bought the cheap evga 9800 to get more and more stable fps)

Orrr... replace the actual APU, forget about the ancient 9800gt and get a better APU, with better (than the 9800) integrated graphs.
Hope i was clear.

 

[MCID47]

get both, probably. Because your A4 is too old for now and dual-core cpu is now out of vision from game optimization.
if you're on a really tight budget, get an A8 or A10 of 5xxx series, so you don't have to change your entire system configuration. But if you have a good budget and future-proof plans, then get an i3 with Skylake architecture or something like that because FM2 system now is getting old and rusty.

 

[Ecky]

^ This is good advice. The A4 is a terribly weak CPU, but even the best AMD APU's integrated graphics is only a fraction as fast as an R7 360. It sounds to me like you're being more limited by your integrated graphics, so I'd recommend first a GPU upgrade. You can carry that over if you decide to upgrade your CPU too.

The RX460 is far faster than the 360 and when I glanced at Amazon and Newegg, they were priced similarly. However, be aware that you might be better served with an nVidia GPU such as the GTX 750Ti or 950, or maybe the soon to be released GTX 1050. AMD's DX11 GPU drivers are much more CPU-heavy than nVidia's resulting in worse performance, even when two competing GPUs are otherwise equally fast, when paired with a slow CPU. There's some irony here that AMD's CPUs generally make up the bottom-end of the market, and that their own GPUs are a worse choice than their competitors to pair with their CPUs, while it doesn't matter as much with a faster Intel chip.

 

[Karadjgne]

Both, sort of. I'd not spend extra on another APU. Instead go for an 880k, which fits your fm2+ mobo, but is all cpu, not a hybrid like the APU. APU's have limited memory access, like Lcache, so pound for pound won't compete with a non APU cpu. No point in having an integrated igpu on die soaking up ½ the actual chip, when paired with a dedicated gpu.

 

[joglesby1]

Well I assume you are on a serious budget considering you are mulling over APU's. I'm a little confused because the whole point of getting an APU is to have decent integrated graphics and have no need of a GPU. Anyway, if you have the money, you should get a new processor(not an APU) and a decent GPU, but many of these upgrades, like any intel cpu, will require a new MOBO. FM2+ socket is pretty bad to be stuck on for future upgrades. If you have a really limited budget you should just get another APU, like a A10-7860k, or something similar. At least another 4 GB's of RAM would be a nice upgrade for you too.