You would be much better off to ask the questions related to award availability and fee involved, in the related program forum rather than a blanket question here.

Each forum of the correctpondent programs would have readers who have more insight to that program to provide you better advice in relationship to the particular award you have in mind.

As for the mileage requirement that you can easily look up on each program's chart. The difference is not that much, about 10K to 15K, so not a biggie. I wouldn't worry about this as finding award seats is far more important than the cost of miles - because no availability, no award, even it is a "cheapest" mileage, it would be of no use!

What matters is the program rules, availability and fees. Program rules again you can find it on each airline's website - such as specific routing, any limit to partner, whether stopover is allowed... each program is different and you have 5 or 6 programs here. No one could give you a generic total picture.

Among OneWorld members, BA is your worst bet for cash outlay due to the high fuel surcharge (YQ) - you are looking at $400+ r/t at least versus AA may cost you $100 or less. BA, AA and AS would all be using CX or possible JL depending on situations They are all One World.

UA/CO you have either UA or CO metal, as well as their partners such as NH and SQ.

Ditto for Aeroplan - because they are all Star A.

AC also charges high YQ on its own metal. Luckily it does not charge YQ on partner flights. So you would look for Star A partners for your trip if you use Aeroplan.

However, every program has its own rules, even UA and CO rules are still different until Next Year. I dont think I can emphasize enough that the starting point is to understand how each program works then decide which one would be the one you concentrate on... because a route is allowed on program A, may not be allowed on program B... In order to find award availability, routing is very important. For example, originating from LAX you would have a very hard time to find any F or even J seat on CX. I can tell you right now the whole November has NOTHING outbound LAX, nor SFO, nor even YVR. You have much better luck from ORD or YYZ. If you are using BA miles, the Single Partner award means you would need to pay your own way to the CX gateway if you cannot find award seat outbound from LAX... So if you find seats from YVR, you would need to pay your own way LAX-YVR, or wherever CX departs and award seats are available on your date(s)...

Again, you need to ask your questions in each airline's own forum for that particular program then make your own analysis. Else you would be just getting incomplete info.