After reading through this thread and Alex's excellent CD-R guide, I've went down a bit of a rabbit hole with this and after a bit of trial and error, I seem to be getting good results on my SCPH-5500 console.
I've done a few burns now with a Lite-On iHas124 Y, (it's a sata drive manufactured in October 2009, and it seems to be near identical to the iHas124 B that wolffangalchemist had success with earlier in this thread) burning to those 80 min CMC Pro "Powered by TY technology" discs at a speed of 8x.
At first I was using imgburn to burn them, but after a bit more research, I've settled on using Alcohol 120% in RAW DAO mode which iirc preserves extra data like subchannel data better than imgburn (CDRDAO is probably the better choice here, but I haven't really tested it yet myself).
Here are the benchmark results from a disc burnt with that setup, a C1 average of 0.3, maximum of 22, and total of 976, which as far as I can tell is REALLY good. Just for fun, I also tested a scratched up original FFVII disc, and that recorded C2 errors (the really bad type!) at a maximum of 5,209 and a total count of 53,438!
View attachment 431911
Before settling on this drive, I tried a cheapo usb external drive which worked about as well as you'd expect (the PS1 wouldn't even detect the discs), and then seemingly had success with the interal drive in an old Dell Optiplex 3040, but I haven't benchmarked the disc from that, and I expect it'd be a lot worse than the iHas124.
I have noticed quite lengthy load times on the PS1 compared to original discs with this setup, but I assume that's just the nature of the 80 minute discs causing the laser to overseek.
Interestingly (and a bit out of scope for this thread), when using the exact same setup to burn a disc for my PC Engine Duo (which reads original discs perfectly), the Duo just spins the disc forever and never loads anything (it sounds like the laser is trying to read the disc, gives up after a while and then restarts, which sounds like a fatal overseek sort of error to me).
Since it's an older console, I bet it just can't handle the 80 minute disc, so I went searching for some good 74 minute discs.
After checking literally every local charity shop, I couldn't find even a single cd-r, but after checking online ended up finding some Taiyo Yuden discs that are apparently 74 minute discs! I also ended up finding a Plextor PX-708A drive cheap, so I'll update here once those arrive to see if they can improve the long load times on the PS1, or get a game working on the PCE (I'm also interested to see if the C1 error performance is better than the 80 min disc + iHas124 combo).
I'm also keeping an eye out for cheap CD-R's online, and I'm gonna grab as many unique ones as I can to try and collect some more data on which ones are good, and hopefully I can get a nice little spreadsheet going of their error rates, load times etc.