I have evaluated this exact question several times in the past 10yrs, and every time i decide it is best to remain with AS.

i grew up inside an AS plane (from ANC), but have been in the midwest the past 10 yrs. when i first moved to the midwest AS had the one ANC-ORD flight, and that was it outside of the western US. now there are 3 flights a day to SEA from ORD, plus other east coast service. i fly about 80K a year, and i would say about 30K of that is on AS - as i fly them from ORD to SEA and ANC. i love the possibilities it gives me being Gold on AS - i can get EQM on AA, DL, and NW - so pretty much i can choose which airline i want whenever i go places. I am getting the 100% bonus for these partner flights, and the 50K bonus for reaching 75K on AS and its partners throughout the year.

the major benefit to switching is first class upgrades - but i can handle Y on short hops around the midwest. i really want the upgrades on ORD-SEA and ORD-ANC - which i always fly on AS. so it just made sense for me to stick with AS.

i did write NW and tell them I was going to switch from AS to either AA or NW a few years ago, and they did comp me NW Gold for the remainder of the program year. yes, i got a lot of FC upgrades, but the miles just didnt seem as valuable to me as the AS miles (with all of the partners it is much easier to redeem somewhere - you get most of the NW partners and more). i flew NW almost exclusively for a year, but it didnt beat out AS in my mind.

i also wrote AA with the same proposition (and got nothing at all back). they do have a challenge program, but there FC is limited with upgrade points. they fly mainly old MD80s, which, as you know from AS, arent the best planes, especially after they created LRTC. as an AS elite i cant reserve exit rows in advance, but again am able to survive anywhere for an hour or two.

i have stuck with AS. although i know that AS has had its share of problems, it really is a good airline and a great frequent flyer program. i dont find AS to be any worse than either NW or AA - the service level is actually higher on AS than it is on the other two carriers. delays plague both NW and AA when flying out of the midwest (i dont think i have been on an on-time AA flight this year - and i have 16 AA/AE segments this year). AS is having some growing pains, but i think it is still a top notch program.

as far as a chart, this is the info i gathered over the years in making my decision (please correct if any is wrong)

LEVELS
AS
MVP 20K (AS only) 25K (AS + partners)
Gold 40K (AS only) 50K (AS + partners)
AA
Gold 25K
Platinum 50K
Platinum Exec 100K
NW
Silver 25K
Gold 50K
Platinum 75K

UPGRADES
AS
unlimited - MVP 48hrs, Gold 72hrs (unless Q+ then time of booking)
AA
4 500 mile segment upgrades per 10K flown
can purchase more
exception - platinum executive get unlimited upgrades
upgrade windows - Gold 24hrs/Platinum 72hrs/Plat Exec 100hrs
NW
unlimited - Silver 1 day, Gold 3 days, Platinum 5days

CHANGE FEES
AS
waived for MVP Golds only, others subject to $50 fee
AA
waived for Exec Plat only, others subject to $100 fee
NW
waived for Platinum, others subject to either $50 or $100 fee depending on market

STAND BY
AS
pretty liberal, unless on a flight-restricted ticket
AA
$25.00 same day confirmation (within 3 hrs)
or you can choose to stand by for free same day
NW
$25.00 same day confirmation (within 3 hrs)
or you can choose to stand by for free same day


MEALS
AS
eff. Aug 1, BOB in Y on mid-range - still comp on transcons
AA
BOB in Y on all flights including alaska and hawaii
NW
BOB in Y on all flights including alaska


PARTNERS
AS
AA, AF, BA, CO, CX, DL, HA, KL, LA, NW, QF
AA
oneworld (including BA, QF, CX, IB, LA) + AS
NW
sky team (including CO, NW, DL, KL, AF, KE) + AS


LOUNGES
AS
discount for being elite - allows use of CO/NW lounges when traveling those airlines - access to DL lounges in ATL/CVG/SLC
AA
discount for being elite - lounges throughout country, but pay for alcohol
NW
discount for being elite - ability to use any DL/NW/CO lounge at any time