Given the original system has a gate and pristine comm relay, there's no reason not to call it home. I agree the Terran planet should be your first colony, and the 175% barren world is perfectly fine for a second. Keep in mind, you can have profitable planets without resource extraction.
If I found such a system in my game and had 1.5 million in the bank, I'd colonize the Terran world immediately. I'd aim for a farm + mine + light industry + commerce, since that would be a solid money maker on the cheap. I would then eye the lower hazard barren world to be fuel production + heavy Industry + refining + military base/high command if monthly income was stable and positive. Such a barren world (presumably hot?) would get benefit from all potential matching colony goodies you find with no downside. And it doesn't matter what it's base resources are since I wouldn't be mining there.
Alternatively, I might trade profit for being hands off by swapping commerce for a second military base/high command. Once you have 2 good sized military bases with heavy industry + nanoforge, you can start to ignore raids by factions as the local defenses can handle them.
The volcanic world might be a later game project if you play that long, dropping a Mining + Military Base combination on it, assuming I wanted to be fully self sufficient, and the Terran world was developed enough to make paying hazard pay trivial. A single source of normal ore (not transplutonic) and no other mining resources is probably not worth building a mining industry for, even if it is +3.
Between exploration finds, AI cores (if you choose to farm them), and story points you should be able to make a fairly cozy home system I think.