i'll say x260, mainly due to x250 issues eliminated (i.e. cracked manifolds) as well as no rusty rear subframe (x260 is alu), when today, x250 is at very high risk of.
go for xfs 3.0 v6 diesel (as you know already, 2.0d ingenium is very risky one to own), very reliable and great mpg for what it is. mapped mine to 350bhp/780nm's and i'm getting 50-53mpg on motorway cruise at motorwaty speeds.
x260 xfs's are usualy very well specced as well, but need to watch out for thigs you want to have, as with x260 nearly everything came as option 🤨 so don't think it wil definitely have it, same as x250, when nearly everything was as std.
good luck and keep us posted.