Which of these programs are better and has more benefits? What are the differences about these two programs?

Welcome to FT!

Oneworld is a marketing alliance, Asiamiles is Cathay Pacific's frequent flyer program, so apples and oranges.

Where do you fly, how often, in what class of service typically? With those questions answered you can start deciding on affiliations.

I fly 2-3 roundtrips between Asia and LAX and couple more time within Asia in the year
I usually fly economy and sometimes in business

Thanks

Does accumulating miles on AsiaMiles give me any OneWorld tier status?

Cathay Pacific has a separate elite program, called Marco Polo Club. It's MPC that grants elite status based on AsiaMiles accumulations, etc. http://www.cathaypacific.com/cpa/en_INTL/ffp/mpo

Note not all Cathay Pacific economy fares earn points on some programs, including AA.

So I�m a member of American�s AAdvantage program. Which means I get points (sometimes) when I fly on OneWorld partner airlines, such as Cathay Pacific. Still, I�m wondering if it�s advisable to join Asia Miles of Marco Polo also, if I frequently fly Cathay pacific. I was under the impression that anything I earn flying them would get me points because of my status with AAdvantage, but I�m not sure. Any advice? Also, what�s the diff between Asia Miles and Marco Polo?
Thanks!

See the post aboveAA Status has nothing to do with points accumulation. It depends on the ticket - fare basis

With your flying pattern, I would consider joining CX's program. You have 2 options that way: 1. Join the Asia Miles program, which is CX's mileage program that allows you to earn miles towards rewards, or 2. Join CX's Marco Polo Club, which is their Elite program recognized by oneworld. By joining MPC, you're automatically enrolled in Asia Miles as well. So you can earn miles to spend as well as miles to advance your tier if you are a member of the MPC.

Your pattern is similar to my own; I fly to Hong Kong from JFK about 4-5 times/year. It's ideal for me to use the CX program not only because it's my main route, but within the US, if I fly AA, MOST fare-classes still earn Asia Miles. If you were an AAdvantage member flying economy to Asia on CX, you'd have to buy the top 3 highest fare classes on CX to earn any AAdvantage miles. Another perk is that with my CX Gold card (oneworld Sapphire), I get lounge access even on AA domestic routes when not even their First Class customers get access unless they are AC members.

Downside: The earn/burn ratio in Asia Miles is pretty poor. There are no bonus miles aside from class of service and the occasional promotion. But the benefits of MPC within Asia are great.

There is more, but that's called the membership guidebook . Hope that helps.