What are you goals here?
I don't want to tell you I regret my V4 Autotrickler and wished I had put the money towards a Prometheus, because it all you want to do is ring steel or shoot animals out to a few hundred yards you can do that with a Lee Loader and a positive attitude.
Mainly what you pay for past a certain point is more speed at the same quality. You could go your entire shooting career with an Ohas manual balance, a Rock Chucker, and some Lee dies and never want for anything, shooting just as good of loads as guys who spent 10X money, just maybe not as many rounds as them.
Direct answers:
-What is the tool/tools you've purchased and never used or found useless?
Cheap measuring tools are about the only thing I'll call useless. I got some Mitu digital calipers and have never looked back. No more dead battery in the cheap digital calipers every time I grabbed them.
A better bench. I'm rebuilding mine, again, because it never seems stable enough. Even before a scale, a rock solid bench to put it on is a must. My new bench will weight something like 300# when I'm done with it, will be on anti-vibe machine levelers, and have multiple Inline Fab plates routed into the top.
There are some things I don't use often, but still don't regret because the one time I needed them they really bailed me out and probably saved me multiples of what they cost chasing problems - 21st Century concentricity gauge falls into this category. The Hornady equivalent I regret because I didn't understand at the time just how terrible their instrumentation was - I was expecting functional and received useless.
-What's the tool/tools that you wished that you would've purchased earlier in your reloading journey?
Mitu digital calipers. A&D scale and V4 AutoTrickler (yes even though I wish I had a Prometheus now). My own reamers/gauges.
I very much so like my Primal Rights CPS primer. I need it because I physically cannot run a hand primer with how bad my hands are these days. Maybe a hand click primer would be a better combination for you in that it's less expensive and maybe more accurate because of feel and whatnot like some people claim, but I can't do that it's a moot point to me. A 21st Century priming tool is probably awesome, guys rave about them, but I can't use it.