What transmission are you going for; manual or auto? The RV after three years may actually be better on an auto-shift equipped unit than a regular manual. If you’re going with a manual then the Servoshift option is definitely worth taking up on the XF, while the new generation Volvo’s have experienced a few probs with the shifting mech on some manual versions.
On the engine side, the Volvo’s D12 lump is virtually a generation ahead of the Daf’s XE motor, and is probably a little better on fuel. Volvo is constantly upgrading its engine software, and now offers a Economy Power option on the 460 which gives 500hp in top gear only - worth asking the salesman about if you’re going through the mountains. Daf’s motor likes a few more revs so if that suits your driving style then you may be happier there …
Overall it’s a close call - if I were in your position I’d probably be looking at who gives the best R&M package, and which dealer you have the best relationship with: which one can fit you in for a service at short notice, which works round the clock, at weekends etc.
Craig