So if I was going to get a second amiga, which?

[spirantho]

ALL Amigas require cap changes. Electrolytics are only specified for 20 years, and they're all more or less that age now.
A600, A1200 and A4000 use substandard SMT electrolytics, though; the through-hole ones in the A2000 (A3000? Never seen one) are ok but they're still too old to be classed as "safe" now.

That said, the earlier Amigas are likely to keep going longer than the 600/1200/4000 because they used better caps, so it's likely that with one of the later ones will need its caps replacing sooner rather than later, whereas an A500/2000 will probably be ok.... but even then it's still only a matter of time.

Personally, I like to recap anything past a certain age. My A4000 is fully recapped, I have an A600 behind me that's recapped, and I have an A2000 next to me on the desk that is - you guessed it - fully recapped.

[spirantho]

Look up "electrolytic capacitor" on Wikipedia for a better explanation than I could give!

It's not a difficult job, but it does take a bit of practice and you need the right equipment. It mostly just takes time. If you do do it, make sure you use a good, fine, temperature-controlled soldering iron for through-hold capacitors, and use an SMT rework station for the SMT capacitors.

If you've never done soldering before probably best leave it to someone else until you've had a bit of practice. And don't worry too much, your Amigas won't just suddenly blow up now you've read that capacitors can get old. Just keep an eye out for symptoms (screen interference, long boot-up times, distorted sound, that sort of thing.. anything that just seems "odd" is usually capacitors!)