So, I have decided to put further posts about my experiences with early Intel Macs in this thread as opposed to making a new one.
I've changed my OS setup since I started this thread. I currently have a dual boot of Lion and Leopard. I noticed that Snow Leopard doesn't play nice with apps that use SDL2. I tried to see if these apps would work in Leopard and they did. This led me to explore Leopard on this Mac more and I realized how useful it is on an Intel machine. Most of the software I use on OS X is Leopard compatible to begin with, and TFF Intel works great on Intel Leopard. I remember a time not too long ago when Intel Leopard had no modern browsers at all aside from running TFF G3 in Rosetta. Another nice thing about Leopard is that it still has HFS Standard write support, which Snow Leopard and later lack. I have 68K Macs in my collection, which use a SCSI2SD device in place of a traditional HDD. The micro SD cards it uses have to be HFS Standard formatted in order for the Mac to boot. With Leopard on my MBP, I can put these micro SD cards into my multi card reader and read and write files to them with ease. On Snow Leopard, I can copy files off of these cards, but can't write any files to them. All of these factors (having mostly Leopard compatible apps to begin with, Leopard having a modern browser when it didn't have one before, being able to keep up with new PowerPC OS X software created by members of the community, and being able to write to HFS Standard volumes) led me to switch from Snow Leopard to Leopard.
Of course a situation could come up that requires a newer version of Mac OS X. For this reason, I chose to give Lion another chance. I'm planning on fixing up my old 5th Gen iPod and part of the process will involve doing a software restore to this iPod. From what I understand, older versions of iTunes may not be able to do this and, supposedly, it is easier to do a software restore on Mac OS X than on Windows. I already purchased Lion awhile back so I figured why not give Lion another try and see if maybe I can use it to restore the software my old iPod? So I backed up my Leopard install to a DMG, repartitioned my SSD, restored Leopard to one partition and installed Lion on the other. Lion runs noticeably slower than Leopard, but it is not awful. The version of iTunes that Lion runs (12.2.25, I think?) is from 2015. Hopefully that is modern enough. Won't find out until the parts come in for my iPod and I can get to fixing it after over a decade of it being broken.
I tried out Firefox Legacy on Lion and it does have some advantages over TFF. YouTube seems to load up faster and Discord is actually useable, slow, but useable (text anyway, haven't tried voice).
My plan is to have Leopard be my main OS and only use Lion when necessary.