I've been very happy with my Qidi Q1 Pro. I paid about $350 pre-tax off Amazon almost a year ago (Black Friday). For me, it was the most machine for the lowest cost I could find. It almost fits your desired print volume (245 x 245 x 240), but it is fully enclosed and has a dedicated chamber heater. I have almost exclusively printed ABS at a 60 deg. C chamber temp. It runs open source Klipper firmware, but I'd imagine repairability wouldn't be the best. Best of all, I have not needed any calibration. It seems pretty spot on out of the box.

My Voron is hands down a better printer but also required significantly more investments in components and especially time.