Hi Anton,
having just completed an almost 3 year evaluation process which ended with the purchase of a plane I least expected ever to be able to afford, I can just advise you to keep your options and eyes wide open. It is a buyer's market right now and there are many aircraft around for very few money, some of which are worth a lot more than the actual price they realize. Also, many sellers will come down in price considerably once they actually have someone on the line who is genuinely interested. You say 25k Euros to buy plus another 15-25 to modify and upgrade, that also translates to me that you might want to have a look at something a bit higher than 25k that does not require an upgrade
As to the types. I have done a lot of research over the last 3 years, some with the help of the folks here. I did have a close look at the AA5 and I agree it is one of the best choices in terms of budget vs performance, especcially in cruise, not so much in field / climb performance. They will outrun their Piper/Cessna counterparts easily, the LR Cheetah has one of the best ranges I could find in that segment and if you are talking 2 people all over Europe, it might be a good choice indeed. As it was said before, the range of types is quite comprehensive and they are very different in profile.
I have compiled a range comparison for most of the airplanes I looked at, all of them at 6000 ft with 65% power and 45 minutes reserve. All figures I quote are from this table with these conditions.
AA5= Traveler (150hp), that one was the first one around. It will do around 110 kts and take you some 340 NM on it's tanks.
AA5A= Cheetah (150hp) has the speed mods over the Traveller and that will give it an extra 5 kts, about 380 NM range. There are two different fuel capacities on the Cheetah, standard (37 USG like the Traveller) or long range (51 USG like the Tiger). The 51USG one will do 600 NM in one stretch.
AA5B= Tiger (180hp) is one of the best load haulers and also does a nice speed. It will do about 130 kts @ 65% and take you about 500 NM over the course. It can not take Mogas, which the Cheetah's / Traveller can with an STC, major cost factor.
Payload: With full tanks the Traveller and Cheetah can take around 360 kgs, the Tiger around 440 kgs. With full tanks, that translates to about 270 kgs for the Traveller/Cheetah with 37 USG and to about 220 kgs with the LR version, the Tiger again scores high with around 300 kgs. So as a tourer, the Cheetah is a 2-3 seater whereas the Tiger can do with 4 if it has to.
As I said, I was looking for a long time and considered several Pipers and of course the Grummans, which were harder to come by in Switzerland however. I finally got a very good deal on a Mooney M20C, so that is what I fly now. That one will do 140 kts @ 9 GPH and has an approximate range of 600 NM too, will take 2-3 people all the way. There are some rather attractive priced Mooneys around, the pre-201 variants are quite interesting. If they have, like mine, the manual gear and flaps, they also won't go overboard on maintenance like other retracables do.
With your budget, you might want to look at the Robin HR100. I have seen 2 Royals around (200hp) on Planecheck, one of them is around your budget with fresh annual and in a very good shape. That one is extremely flexible in range/payload. It will take 4 people about 500 NM or 2 people 950 NM, it's metal so it is not critical towards weather (of course hangarage is still preferrable, but that goes for all planes) and it will do so at about 130 kts.
One thing I have found out while researching my choice of airplanes was that speed will save money when it comes to touring. Even if the hourly rate of a higher performance plane will be higher, it will bring this back with the shorter flight time. If Mogas enters the equation, the cost will however change again, so the Cheetah is a very viable variant here, but if you calculate Avgas, a pre-201 Mooney can do comparable trips cheaper than, say, a Warrior or an Archer, just due to it's speed and lower specific consumption.
I have learnt during this very interesting time that keeping your eyes and mind widely open pais out tremendously in this enterprise. I had looked at Mooneys and the likes like a 3 year old in front of the toyshop, never imagining I could ever afford one, but today's market conditions are really a buyers paradise. There is a huge variety of planes at prices which were unthinkable a few years back, which can allow you to up your expectations quite a bit. So if you say 25k for a plane you wish to upgrade, why not spend the whole amount on something which does not need upgrading, e.g. is IFR equipped and you'll just have to enter and fly it? They are out there. And even if the add sais 40k, it doesn't hurt to ask, I have understood that some planes went for less than half of what they were advertized for.
Anyhow, sorry for the long message, I hope this gives you some information. If you are interested in my comparison sheets, pm me.
Best regards
An2 Driver