I work hard to find good quality cables and accessories that don't cost a fortune. Most cables are not of good quality. Best quality are always originals, or good Japanese third party such as Hori and other brand names.
Recently I have been on an obsessive quest to find good quality pokemon batteries. I have my own way of testing batteries, and they always drain much faster than the original Panasonic batteries. There is a big difference between a good battery and a bad one in battery life.
The noname batteries are bad, but there are also counterfeit batteries, such as Sony batteries... these look suspicious..
In the original carts, NES batteries have often lasted since the 80s, more than 25 years ago. All NES, Game Boy and SNES games that save data have batteries in them. Usually all RPGs. Batteries last longer if kept cool. People that left their games in the sun they might by more likely to have dead batteries in them by now.
A small number of GBA games have batteries too but most have a flash memory, from what I have read. I once had to replace a battery in Densetsu No Starfy.
I could write a long post about cables too.... I have received cables that don't work at all, or that come off too easily. My ambition anyways is to use the best quality products that aren't too expensive.
Original cables aren't made anymore and can be hard to find. For example, on the SNES many people used antenna output (I did), and some used the multi out with RCA. RGB was the least common choice, and that is why an original Nintendo SNES RGB/Scart cable can cost 250-300 SEK (35-40$) or so. The same price for an original MD RGB/Scart cable. You can find third party replacements for a quarter of that price, and as far as I know there's nothing wrong with them. But some of the cheapest cables on eBay will pick up interference, and the connections are bad.
It is weird when I think that I played on a 50Hz PAL SNES with antenna output. A 60Hz console gives much better picture than 50Hz. When I plug in my old SNES I think it is broken due to the flickering picture. ( And here I would like to note that we can easily modify a PAL SNES with 50/60Hz switch, but note that some PAL SNES games might glitch )
RGB gives a picture like playing on the arcade, although I am not an RGB fanatic as much as others. I bought a multicable with Scart a while ago and I use that for Saturn and Super Famicom, and occasionally Dreamcast.
On my old TV it isn't a huge difference, but if nothing else it saves me the time to crawl to the TV and change cables.
Well if you have any questions just post a comment. I could say more about cables but I wish I knew more.