It all depends on route and timing. If we are passing through an area where we feel safe to leave the van for an hour, and have time to do so, and there is suitable parking, we will often stop for lunch and a wander round.
For instance, if we are heading home from the South East along the M4, there is nowhere worth stopping suitable for with a van on the back. Solo we often go into Chepstow, but there is no parking for a unit.
On the other hand, if we are returning via the A40, we will often stop at Abergavenny, where there is good parking and a decent lunch.
Somehow it seems more of a rest to get away from the unit for a while for lunch.Most motorway services seem to be OK if you go in the lorry bit, though this is just functional, with very few exceptions there is nothing appealing about Services!
The exception is Tebay (M6) which has an organic and local food shop, good food, good views, and a caravan site.