(...) you can recommend settings to go against that and get me outside of my comfort zone or whatever you think will be funny
Well, check the "Outa Tracks" thread
here if you really want to challenge yourself. Maybe we could jump on this thread and go through the question-anwser "what's your playstyle?"; "then this and that options will be challenging". But I recommend you go for something within your playstyle first, if you prefer to get comfortable before tackling bigger challenges.
For the raw difficulty, I recommend 7/7, if you were far ahead of your level at 5/5.
If you want a thematic setup, let me propose you my lobby scripts:
here. There is one script for each galactic race in the game (Spire, Zenith, Neinzul) plus one for humans. (Dangit, the files are a bit further down the thread.)
If you want lore, I recommend you to play the Light of the Spire "campaign". If you do, consider doing so without other mods, with a vanilla map style and easy AI types to stay focused on the campaign.
Speaking of that, maybe you could try something special with the non-Minor-Faction options. Try an original mapstyle, like concentric, wheel, clusters or grid. Or try an exotic AI types combination, like GravDriller/OneWayDoorMaster, or anything you want to experiment. (Just go through the list and say "Oh, nice name, I wonder what this one is doing. Let's try it.")
I recommend not playing with pain-only minor factions, like the devourer, miners, hybrids or astro-trains. First, get comfortable at your raw level (7/7?) then spice it up with MF, then upgrade the raw difficulty and clean the options (vanilla 8/8) before spicing it up again (8/8 + MF), etc.
Alternatively, you can toy with superweapons. Enable Golems, Spirecrafts and Champion and have fun. Beware not getting used to it, however. It took me a certain amount of time (and death) to drop the superweapons and get back to vanilla 7/7. My first home assault when I decided to quit the superweapons was... challenging.
(BTW, if you want a "mining" theme, enable spirecrafts at easy and balance it with miner golems. I'm sure it could be fun).
Hey, that post is longer that I thought. Anyway, welcome back, nice to see you again, and have fun kicking IAs in the teeth!