Buy the biggest colour screen moving map GPS you can afford. That's what a GPS is for: superior situational awareness. End of story.
If you want something which will give you the lat/long (for when you are floating in the life raft and calling the coastguard on the mobile phone) get a £100 GPS from a camping shop
Get a remote aerial for it, attached to the top of a window with a suction cup.
Other than that, it's a personal preference. Personally, when I was renting, I used to prefer leg-strapped units, and most Garmins can't be used like that.
Today I would buy the Avmap EKP IV - not cheap. It's sold by various pilot shops in the UK including
www.flightstore.co.uk. Not cheap but very good.
The next factor would be whether you want to use flight planning software, and for Europe Navbox is by far the #1 choice, and you may wish to be able to load the planned route straight into the GPS. Unfortunately Navbox doesn't support the Avmap...
Having said all this, most people asking this question don't have the budget.