A year of 4-5 ago i would've said HERE but recently I feel TomTom has caught up and even got better then HERE in the Netherlands imho. I can find a lot of smaller (secondary) streets using TomTom that I can't find using HERE maps for iGO.

According to HERE 2017.Q4 maps the closest I can park to the apartment i live in is 50 meters as that is the closest main road that is on HERE maps. TomTom 2017.12 maps also has the secondary smaller road that leads to the apartment and the parking lot in front of it so I can navigate all the way to the "front door" with TomTom but can't with HERE.
This is just one example of (smaller) roads that TomTom does have and HERE doesn't.