I'm gonna go totally out of the thread here and say also consider AA or AS (with AA partner benefits). If you're at all even looking at non-*A ffp's. :P
Let's assume you make ~50k tier on each airline
YVR-PHL
AC: via YYZ, Tango 25% to YYZ then 50% to PHL
UA: via ORD, 100%
AA: via PHX/LAX/sea, non-stop from SEA 100%
AS: same as AA, 100%. Own metal: non-stop or via SEA, 100%
YVR-SFO
AC: non-stop, 50%
UA: non-stop, 100%
AA: via LAX/PHX/sea, 100% or non-stop from SEA
AS: same as AA, 100%. Own metal: non-stop or via SEA, 100%
YVR-FRA
AC: non-stop on LH (50%) or AC metal via YYC/YYZ/YUL (50%)
UA: via ORD
AA/AS: Via DFW(AA)/LHR(BA), 100%
50k benefits
AC: E+ on NA flex and up, 3 bags, up to 40eUPs (only flex and up, e.g. 1 YVR-YYZ-PHL RT), 50% RDM bonus
UA: E+ at booking on any fare, 2 bags, unlimited (...very rare? upgrades on all fares), 3xUSD RDM bonus, free SDC
AA: E+ at booking on any fare, 2 bags, 16*500mile upgrades (so 8'000 NA miles upgrades on any fare, e.g. 1 YVR-DFW-PHL RT. extra upgrades purchaseable), 100% RDM bonus, free SD-standby (though becoming 3x USD RDM bonus next year
)
AS: E+ on AA&AS, 2 bags on AA&AS, unlimited (rare? upgrades on all fares), 100% RDM bonus, free SDC. Also some benefits (stil...) on DL and arguably the best award-chart of all FFP's...
Somebody please correct me if I'm wrong about any of this.