GH test kit was the first one I used. Worked well, but I felt I needed more precision.
Had a Hanna checker die on me pretty quickly. It went way out of wack and couldn't be recalibrated.
Tried pH test strips, but again, hard to see the difference between 5 and 6. I'd use these for soil though. I've also seen some with better resolution than mine.
Picked up eBay copies of a pH and EC Truncheon most recently. I check every couple of weeks. They have enough precision for me. Happy so far.
Once I switched to RO filtered water, I don't need to monitor that closely anymore.