Was looking at how the UK BA Amex PP vs this ES IB Santander offer:

UK BA PP
£300 AF
1,5x avios/£
3x avios/£ on BA
Companion voucher at £15K spend, once use, use any time

ES IB SD
€48 AF, but get back €24 back for the monthly 200 avios (@0.01)
0.5x avios/€, mastercard so everywhere taken, though there's 1:1 with amex plat
IB spend 25% avios bonus on the 5 avios/before-tax €, assuming tax is 25% of the fare, then = 0.75*5*0.25 so 1x. So 1.5X together with above 0.5x, closer to 1.76X in GBP. And bonus 1x is only for the account holder, if booking for 2 pax, the extra 25% bonus for the second pax is not given, whereas BA one the card holder gets 3x on total spend for all pax?
10% on IB flights (even on the tax component), but not IBX, still wins back all the lower avios earning.
Random Santander flying days 50% avios redemption offer, unlimited use, depends on luck if the flying days happen to be a year from when you want to travel to get the J/W seats.
OWR apparently, but not relevant here.

Overall the BA PP is better for once a year big holiday planned a year in advance, as the value there is higher than all the IB ones together, unless the there's so much IB bookings the 10% savings is worth higher the BA companion savings.

Wonder when the Amex-Iberia (Spain) will return though.