We remodeled the kitchen and bath, new lighting and hardware, refinished hardwoods, replaced the fuse box with a panel, replaced galvanized lines, painted throughout and partially finished the basement.

This post is purely opinion based although I suppose some may have experience with this.

Replace the HVAC that you thought you could get a few more years out of.

Window screen replacement.

I.e. you can choose not to spend on a 15 yr old roof today, and probably don't need to, but you will have that roof replacement coming in 5-10 years, assuming you still own the property.

Once you get an inspection report, this will give you a better idea of what may need to be repaired/replaced in the future.  

Paint, LVP flooring, IKEA cabinets, replacing outdated light fixtures will save you money if you do it yourself and they aren't highly technical. 

Finally, we are replacing 2 exterior doors and an interior door.

I personally have been focused on replacing my W2 job income with CF.

Said the main cause of the issue was a clogged up air filter (I know, my bad for not reminding my tenant about the importance of regularly changing filters (it's written in the lease that he must replace them every 3 months and that I'm not responsible for bills resulting in replacing filters)).