Leaving aside the weather, I think Ireland is a pretty easy country to fly in.
Outside the Dublin area you've got one frequency for FIS, which will give you a radar service over most of the country.
There is relatively little controlled airspace and what is there is easily accessible (except around Dublin).
Airports are generally easy going.
I wrote an article a few years ago on flying in Ireland and updated it earlier this year. It's written from the point of view of a UK pilot visiting Ireland, and is intended to give them the knowledge that they might need to help make their first trip to Ireland go smoothly.
You guys might find it useful.
Lithuania and other Baltic states are easy. Little traffic, no mountains, inexpensive. Good infrastructure, Avgas widely available.
Obviously a couple of Swedish pilots that used Lithuania as their base to 'raid' Belorussia also did not encounter any problems with ATC and/or NATO air police, which demonstrates how GA-friendly the country is 
The only downside is prolonged spells of unflyable weather, especially in winter.
BTW I have just edited Posting Tips to include the recently added Image and Link buttons.
The "neat" link to Dublinpilot's article is here.
Just use the Link button above the text entry box.
BTW the original two icons are still there...
: smile : (without the spaces) gives you 
: wink : (without the spaces) gives you
Others are on the list...
As I have got around some, I may add my 2 cents.
As "easy" or "not easy" is somewhat up to personal judgement, let me focus on cost. Generally speaking, the further east you go, the worse it gets. The worst places (absolutely unreasonable for private flyers) are: Russia, Belarus, Aserbaidschan. Usually into the four digits for landings. BTW, even though not Europe, Iran is in the same league with those.
Still terribly expensive, but a little bit better than the above, are: Ukraine, Turkey, Georgia. Well into the three digits usually, but really never any less than 250 euros.
Romania and Bulgaria: prices vary a lot, between 100 and 300, give or take. Unfortunately, if you look at the bigger airports, Spain has to be put into this category as well. Well,... at least if you like at "GA-friendliness" and GA-infrastructure of the bigger airports.
After that, basically, in all other countries you can usually land, even at the bigger airports, for around or less than 100 euros. Of, course, most countries have a handful of exceptions to this (usually the very biggest airports).
Back to the subject of "easiness", IMHO nothing beats the northern countries (Denmark, Sweden, Norway, Finland). These countries' services and infrastructures are simply well geared towards GA.
You'll kindly excuse me for being the difficult one, but what are the criteria?
1) ease of VFR navigation?
2) ease of IFR navigation?
3) linguistical abilities of ATC staff?
4) availability and cost of aerodromes, IFR equipped?
5) availability and cost of aerodromes, other?
6) availability and cost of 100LL / mogas / jet A1 / whatever?
7) hospitality at or near aerodromes, i.e. restaurant and/or hotel (or lodge or cabin or even allowance for tent-under-wing)
8) availability of attractive destinations, either pilotwise (interesting approaches?) or groundside (aviation museum?)
For myself, as a microlight pilot, 2) & 4) are totally irrelevant, but 3) makes me disfavour Spain - though only from hearsay, I'll admit. For 7) I think France and Germany are top, but my own Belgian country doesn't do too bad either. But there's very much room for discovery, and eager I am! If I can manage into Italy next summer it will be a great achievement, to be told and retold to my grandchildren.
My private greatest hopes are towards the Balticum, with a (probably overrated) curiosity for Aleksotas EYKA and its museum; and central European places like Hungary, Slovakia, Czechia, Slovenia. Too far East I distrust, as confirmed in the earlier response. Scandinavia may have fine airspace and lovely aerodromes, but I generally found people on the dull side there. Switzerland doesn't want microlights, and Austria seems to discourage them too.
It's not possible to completely generalise.
Earlier this year I flew to Barcelona/Sabadell. For €80 total I got a lift from the aircraft all the way to the hotel in town centre. I think, given the ripoff taxi rates, this is amazing value.
While Spanish airports have recently jacked up their rates by some outrageous percentage, they are still mostly well below the €100 mark, which is "OK" for the occassional visit. One does wonder how could GA possibly survive there at such rates, but aeroclubs get special rates.
Turkey... depends on who you know. One fly-in I went to was a few tens of (whatever foreign currency). But that was organised by the Turkish AOPA, which is really pro-active and superbly organised. Well, as far as anybody can be in a country owned by the army...
I have got foreign flying relatively well sorted, but the thing I find hardest is getting airports to reply. It's no good relying on the AIP. It might be good, it might be garbage, or anything in between. So I always contact the airport. No reply = no flight there, with almost no exceptions.
But if you can speak the local language, all the doors open up. That's why you can have one person saying such and such is easy, and then Peter tries to go there, speaking the only langauge he knows, and has all kinds of fun
Also much depends on how predictive you like things to be. When I fly, especially with Justine, I want things to "just work". I am not interested in getting stuck somewhere for a few days. We did all that some years back and it's not necessarily pleasant (Switzerland, in the rain, £20 sandwiches ). But a lot of pilots like that, and I won't criticise it.
Many people are afraid of flying to Greece but actually Greece is easy, because checking stuff out is straightforward.
Jan, my initial post is to be read as easy = straightforward, little preparation required, many facilities. Complicated = pre planning required, contacts to be established, few facilities, not geared up for GA.
Let me know when you come to Italy next summer. As a microlight you have access to hundreds of fields.
I forgot to mention Bosnia in my initial post, great destination, just a pity the unavailability of avgas. I believe the 24 hour slot requirement is no longer necessary.
Formally it is mandatory but you can get without it and fill the form on the arrival. However, I can't vouch that everybody will have same experiance - I know all staff there and I can expect "special" :) treatment.
Cyprus!
LCPH Pafos:
Avgas, Jet A1, Hangar soon (we're building it!), Best Mediterranean weather of anywhere, VFR and IFR H24, Lots of varied hotels locally, A growing local GA scene, Flying schools (EASA)
If you get down here let me know, cold beer always on tap!
Nobody has mentioned the land of the clog and the double vowel - The Netherlands is not that bad!
