3 Commando Brigade

i5 or i7?

https://www.cpubenchmark.net/compare.php?cmp[]=2275&cmp[]=2284

I'd say spend the extra and get the i7. Having a stock clock speed of 4ghz is really nice and leaves you plenty of room for overclocking well past that. Both seem pretty nice but I guess it is what you budget can take.

For gaming.. Yes

The majority of current game engines' approach to multi-threading is very course grain.  They divide the game into large chunks and assign each chunk to a thread.  Whilst it kind of works, its really inefficient when the number of hardware threads increases.  This is why currently an i5 with 4 hardware threads is a capable of the same in-game performance as an i7 with 8 hardware threads.  

Now we have the next-gen consoles with 8 cores, we'll see game engine architecture move to finer grain parallelism.  This will take some time, but at that point the i7's will have a significant perf increase over the i5's.

The question then becomes, how often do you replace your CPU and is it worth spending the extra and getting an i7 now.  In most cases the answer is usually buy the i5 and then replace with an i7 (2 generations down the line) when game engines catch up.

It also depends on the games you play.  Arma for example uses threads really inefficiently. I see very little use of hardware threads past 4.