What parts should i buy?

For gaming, i5 would do fine for time being. In 99% of cases just as good as i7.

Also, if you wanted to compromise a little, you could look at AMD ryzen. The single core performance is worse at the moment, but for multithreaded performance, that is one of the strengths.

I would suggest though, wait until April, as they are releasing a refresh of ryzen which should be a little faster than the current parts.

But for example, right now you can get the ryzen 5 1600 which is 6 core, 12 threads. Granted for pure gaming, they are slightly behind Intel right now, but if you are playing at 1080p 60hz, you probably won't see the difference. And it should be a massive upgrade over the a10 you have now. In other words, if you went for the 6 core ryzen, you would get the 6 cores and the multithreaded performance a little more comparable to the i7 but pay the price of the i5. Just understand for pure gaming, Intel is a little faster right now. But the ryzen chips are still good at it. They literally did like a 40-50% jump in performance over the previous generation.

I upgraded from an FX 6300 to the ryzen 1600, trust me the new ryzen chips aren't the dogs that their older ones were. I'd say the ones coming out next month should be a bit better.

Either way, with what you are considering, the i5 will be fine today, but more games are starting to rely on more threads. Battlefield 1 is a good example. From what I've seen online, some people have had trouble with it on quad cores. Was reading where some people, even a guy who had an i5 6600k was getting loads of 85% on his CPU, and people with older i5's having issues at times too unless they were lowering processing effects.

When you look at PlayStation 4 and Xbox 1 basically being a PC, they use what an 8 core AMD CPU now? So it makes sense as time goes on that developers will probably keep starting to use the extra cores on CPUs that have them.

Concluding, for today, the i5 is fine, but if you are keeping it a while, get the i7. But if compromising, look at ryzen. One thing about ryzen as well, is they are saying they will use the same socket until 2020. So if you decide you wanted an upgrade, you might be able to do a bios update in 2-3 years and drop in a ryzen 3 CPU and not have to swap out the board, ram etc. Intel usually seems like they require a new board about every other CPU. So that's a cost to keep in mind as well.

Exactly

An i5 8400 or a ryzen 1600 will both outlast a gtx 1060 6gb imo

4-5 years ?? Yeah I reckon they'll do that at a push.

Essentially double the performance with the 6 core i5 as what you have now , maybe a little with the ryzen.

The i5 will push more straight out fps , the ryzen unarguably has a lot more future proofing headroom.

Disagree, you can’t say for pure gaming the Ryzen has more future proofing headroom. It might do but I’d put my money on the 8400/8600k. For Ryzen to step ahead games would need to decrease the dependency on single core performance while offsetting it with extra threads. This all sounds like the same debate when the FX series released and we know how that turned out although games have at least started using more than 4 threads.

If you're intent on intel them yes , i5 8400 & 16gb ram is fine.

I dont see the 8600k as a value proposition really, €50-60 more , add a decent €40-50 cooler & its €100+ more expensive.

Unless you're running a 144htz screen there is literally no benefit.

You should be picking 16Gb regardless of cpu, it the recommended with several newer AAA games. If you want it to last 4-5 years I would go the extra for the 8600k, it has a significant clock speed increase over the 8400 when mildly overclocked. The 8400 is a great choice and may well meet your needs but personally I’d go 8600k and OC when needed.