It's personal preference of course, but I assume you know that using disc images as an archival format is quite unusual.
ALAC files, besides being a bit more compact (which you don't care about) are ready-to-use, playable music files. When it comes time to get your music out of the archive, ALAC will be a more immediately usable format. ALAC, being a lossless format, provides exactly the same audio quality as the CD itself.
Unless your objective is to be able in the future to recreate the physical CD, there is no advantage in having the actual disc images.
Thank you, Ed2345.
Regarding your last sentence ... isn't making a new physical CD pretty much the same process whether disc image or ALAC? I understand you just drop an IMG into Toast and hit burn ... or drop an ALAC into XLD and hit burn. Or is there a step I still don't understand?
It is not actually the same process. The burn from disc image copies the image, i.e. all contents and structure, onto the CD. The burn from ALAC (or WAV or AIFF) reconstructs the audio, creates a table of contents, adds its own gaps, and then burns that to the CD.
However, if your future intent is to use the songs in a player such as iTunes, the ALAC files will be ready to go, while the disc image will still need ripping.