Personally it's the detail for me; how accurate it can look for the real source, the color, etc. If there's enough articulation to give your figure a nice pose then that's good enough for me in that area.

Too often I see figures' faces that doesn't look close to the character, but then again if the figures are of low budget then you get what you pay for?

I don't collect action figures, but I would probably prefer no moving joints. The more detail the better, but quality of build materials is possibly most important of all.

Only action figures I'd collect would be hot chicks (preferably almost naked) action figures, Japanese style cause what can I say, those are usually hot. But those bills in my pocket labelled "Euro" are even hotter to me, so I am not about to exchange those for the aforementioned hot Japanese chicks action figures. Just seeing the pictures you guys put on this and other threads is enough for me.

I generally collect banpresto shonen statues. Affordable and cool looking. Don’t care for poses.

All of it matters.

The ones you've mentioned, plus price point, packaging, scale, variation, 1st issue, reissue, accuracy, brand, and availability.

Just keeping it short and sweet here...