I started to use SatNavs when they first came out. At that time I was spending many weekends doing presentations at various schools and sports centres all around the South of England. Previously, I had looked up directions, and written loads of post-it notes which I stuck to my steering wheel. Even tried making a recording of the directions for me to play back to myself in the car. Sat-Navs were the answer to a prayer.
Over the years had three or four, all different makes. NIcest one one was a Samsung or Sanyo (), which actually said "Please take next turning on the right'........did not say Thank You, when I did.
I ended up with a Tom-Tom - but purchased this when they still wanted to charge considerable amounts to update it regularly, so never did the updates. I think that now these all have free updates.
Finally, I found that my smartphone and googlemaps were, by far, the best - always up to date and always aware of any specific local problem. Soon learned to ignore it at my peril. If it was telling me to use a different road it meant that there was a current problem on the original route.
So, if you have a smartphone, do not bother with purchasing a separate satnav - just use that. If you do not, then I would recommend purchasing ones of those rather than a separate satnav. Sort out a suitable unit in which to place it when in hour car.