I just went through the pain of comparing the Oakton PH2+, Blue Lab and Apera PH60. I have lots of cheapos but I moved to pure hydro and the calibration and the hit and miss was not working and wasting hours of my time.
Oakton PH2+ - This is the newest version, most people are unhappy and want the older model back. Takes too long to PH and jumps erratically.
Blue Lab - This seems to be the go to for PH pens that wont break the bank, but maintenance seems to be tedious.
Apera PH60 - This is the pen I chose, its accurate, fast, holds its calibration, measures 0.01, and the probe is replaceable and interchangable with an ORP, Spear or Flat sensor. Comes in a nice professional case with KCL and calibration solutions.
All of them are similar pricing 50-80 dollar range