What's better about achievements? 

Trophies > Achievements > Stamps for me.

The platinum trophy is the tie breaker on it for me. The fact that you are rewarded for hunting down all the other trophies is nice.

Stamps are useless to me as I don't Miiverse.

Love nintendo stamps

thats also the reason why i like trophies as well, always going for that far in the distance platinum trophy.

Seems like one of the biggest problems for the stamps is that not enough people know about them to care. How would you resolve this issue?

Achievements started the fad, but trophies improved the recipe. Some games screw it up and make the hardest trophy a bronze, or just give you silvers & golds for participating, but usually they make sense. And getting that platinum feels so good.

Do not have strong feelings, but as a model the tiered trophies makes more sense to me. Having X Platinums is easier to understand than a Gamerscore for me. Not familiar with stamps.

Achievements are the best, especially now that on the home dashboard it shows the top 5 friends with the highest gamerscore over the last 30 days. Gamerscore is just much better to compare based off percentage completed and gamerscore earned.

I prefer the gamerscore number compared to levels and %.

steam trading cards!