Morning Marty, I think you are only going to get 2 answers to this mate, Garmin or Tomtom, I fall on the Garmin side and use the 390LM mounted to a BikePenR centre clamp mount. Been very good so far in both UK and Europe. They are all pretty good now from what I gather, but I have always had Garmin, so just stick with them. Waterproof, easy to use and free lifetime map updates.
Not sure you can get a Navihalter bracket now, as the lad who makes them has had a serious accident @Marty, but if you do find any for sale somewhere please let me know.
Ducati dealers are selling the same thing for £69 ea, thread on here somewhere High navigator mount set. - Ducati Multistrada Accessories
Had Garmin Zumo. Went to Tom tom rider 410. Expensive mistake. Sold it and put money towards another Zumo. just could not get on with the 410 operating system. Far too much button pressing required. Reroute option and find petrol option much quicker/better/easier on Garmin. Example, change route due to closed road so you hit recalculate button. Garmin easy. Tomtom a choice of 3 options on the screen that looked like a spiders web. Stupid. Also, twisty road option on the Tomtom was just plain crazy in the Pyrenees. Took us down every back road (often half gravel), the default setting seemed to be based on back roads/tracks rather than plain old windy roads. In fact we seemed to turn off superb roads on to shit ones. Waste of space IMO.
Zumo 590 on RAM mount. Been a Garmin man since having an early Quest model. At that time TomTom were significantly flawed with serious cradle issues and crap support that was in denial. Garmin on the other hand were very well supported by a knowledgeable team in the UK . things have equalised, with both meeting in the middle these days. If you can get a demo of each and make your own mind up. If you have serious explorer pretensions then there's only one choice and that's Garmin.
I've a Garmin 395LM. No complaints, just did a few days in France and found it very easy to use, flawless navigation and a lot of good features. Everything you need is in the box although if you want to accommodate your preferred RAM mount then you're good for that too! Cheers
Got garmin 660 & 595LM, prefer the old one with a high-brightness mode. As now that I ride with a hi-vis on most of the time. I get a reflection of off the 595 & it dulls the top max brightness. I wouldn't re-buy this technology ever. If it breaks its gone, although it can link to the net through a phone link. And do some very neat stuff.