Repairs to AA-5 and AG-5 models are typically more difficult and more expensive than to C172/PA28 types.
A structural repair shop I work with found this to be the case with a firewall repair on an AA-5. It was a big job, where it would have been a moderate job on a 172 (and less likely to have occurred with the PA-28). That said, I have found the AA-5 very pleasant to fly, and quite efficient to operate - repairs notwithstanding.
As a purchaser, you must decide which factors are most important to you, and understand well how they affect your preference in ownership. And, as you progress through your life, those preferences may change. The longevity of your airplane will be one of those preferences.
If you buy a modest plane, with the intent to fly it lots to build experience, and see the value in that "more rapid" use, you're less worried about the "investment value" of the plane. If you're buying a gem, or spending a lot to gem up a plane you buy, you're more interested in retaining it's value - and insuring it! So, if you're aiming to retain the value of the plane, you need to understand what
is involved with doing that (what inspections are required, common weaknesses, and parts/maintenance availability). And, you should get some advice on what
could be necessary (impending inspection requirements, or what is common damage, which may seem minor, but is more involved than you imagined).
There's nothing wrong with buying a modest plane, poor paint, worn out interior, '70's avionics which work, if the plane is mechanically sound, and piling on lots of time, willing to take a risk that something could go wrong, and you simply sell a non flying plane for parts. My first plane (C-150M) was bought with that in mind, in 1987. It was modest, I flew it lots, and did not other insuring it for hull, 'just took the risk. I maintained it, and upgraded it as I could, knowing it was really worth more in parts than as a whole flying plane, so an accident or damage would not make its value zero. I still own it, with an overhauled engine, new paint (a while back), redone interior, and all redone avionics - and I have 3000 hours enjoying it. I never planned it as an investment, and never needed it as one, it just became one, because nothing ever went wrong.
Or, you buy the gem, the plane that someone else has done everything to. They know what they paid to do that. Unless it's their fire sale, they're looking to get their money back out of it (their investment). Or, a very new plane. Now, you got the gem, but paid the price. You'll worry a bit more about minor damage, and endure the cost to insure it well. But, if something breaks, or an involved inspection is required - that's not insured, you're on the hook. And, you have too much invested in the plane to walk away from it, and buy another. Aging aircraft is an issue. It's not new, but visibility is increasing, and poor experience with certain design features is being gained by the industry. While owning and flying my modest C-150, which I do not insure for hull, I was also flying and training the new owner on a C 182 amphibian, which I know that the owner had $900,000 invested in - everything was perfect, and he have the insurance premium to show for it - and I had to do all of the testing and training in it, without scratching anything! Kind of the opposite beater floatplanes I'd load all kinds of cargo in and out of! The first scartch would be mine! (happily, 5 years and 400+ hours later, three of us flying - zero scratches!). But, worry about a new inspection recommended by Cessna, which was not known when the plane was purchased. He can afford the inspection.
But the key is to get your head in the right place about ownership. Most people want to be seen stepping out of the gem plane - Cool, look at that pilot! But, maybe you can't hangar it, can't afford the new paint job, so maybe choose to not own the gem paint job, which you cannot maintain the way you'd like to. Every owner you talk to would like to tell you how great their plane is - and every flying plane has greatness - it flies! But ask a lot, and then consider if the background operating burdens are something you're comfortable supporting for that type. Is a mechanic about to have to drill out some of those newly painted rivets to inspect something which we did not know about a year ago? Maybe accept the plane with the more tired paint job, so drilling into those rivets doesn't hurt so much!