Haven't played the PSP ones, so I'd have to say GOW 3 overall.

GOW: Ascension has the most fun gameplay though and looks the best.

3 definitely. This is how you finish up a trilogy.

can't really tell. only played the 1st on PS2 and thought it was very fun.

GOW III for me. I still haven't found all the piece of my blown mind from that Cronos fight.

I have only played God of War 3 and God of War Ascension.

Of those, God of War 3 was obviously the better game, I thought that game was a very good one and enjoyed every minute of it. Good story and design, good gameplay elements and polished all around. Given that I liked 3 a lot, I gave Ascension a try. Huge disappointment. Level of gameplay was two steps backward and the game suffered from a plethora of other problems that didn't exist in 3. Couldn't bring myself to finish it.

So, for me, God of War 3.

God of War 2 is easily my favourite, pretty much a perfect adventure hack&slash game. I am eagerly awaiting Cory Barlog's PS4 announcement as God of War 4 or reboot, please bring back the epic journey!
I loved all GoW games though, one of my favourite series. Ascension was really close to the 3 for me, uunlike than majority of gamers. Felt more like a sequel to 2nd game in a lot of ideas and design.

GOW 2. The first one is horribly dated. Those rotating spikes, ugh. Ghost of Sparta was well made too. 3 was hit and miss for me at many points.

Time to give this series a long rest. With that said, i'll be playing Ascension soon. So, atleast i can give it a long rest. 

I 2nd game in most new IP game series tend to be better than the 1st and in many cases any more that follow

On God of War it is hard to choose between 2nd and 3rd, but I personally think 2nd was more amazing for its time than God of War 3 (which is better, but not as mind blowing as when 2nd came out).

Actually is funny how my enjoyment of Sony's bigger series seems to differ from the norm.

I didnt particularly enjoy the trilogy. The God of War games i enjoy the most are the stand alone ones. Probably because the narrative was contained and had a conclusion. It also didnt feel unecessarily streched out like GoW3.

So, i enjoy Chains of Olympus, Ghost of Sparta and Ascencion the most. If i had to select one, its no doubt Ascencion. It was an amazing game and since i have no attachment to the secondary weapons, changing the elements of the blades was very enjoyable.

God of War 3 for me. Amazing scale, superb boss fights and the sense of conclusion. This and Kratos is simply ruthless on this game. Second would be GOW 1 (Ares was the best enemy of the series).