It seems to me that the most important consideration would be the ease of getting an award ticket. I would burn the 25,000 on a domestic ticket and then accumlate on Alaska Airlines. It is very easy to get a ticket most anywhere in the world from that airline. American and Hawaiian are partners of Alaska, so it's also easy to get a domestic ticket, or a ticket to Hawaii or Alaska. (The latter is highly recommended for everyone.) And Alaska is not bankrupt and not likely to go bankrupt.

The only problems with Alaska are that your entire round trip flight must be on one airline, and stopovers are prohibited unless necessary to get there. (I haven't tried open jaw with them yet.)

My second choice for accumulation would be Delta.

It is almost impossible to get award tickets from Continental or Northwest.