The only downside with those is that as the liquid drops or capsules age their effectiveness goes down dramatically, and you have no idea how long they been sitting around for before you got them!
I will admit though, they could be accurate as of right now, but there's no real way to know.
Nothing bets a PH pen that is capable of being calibrated, because as long as you calibrate it right its always accurate! And it will stay accurate as long as you keep up with the calibration. (Most PH meters that are able to be calibrated dont come with the calibration solution, you have to buy that separately, but it lasts a long time)
I wouldn't recommend either of these two products for a quick cheap PH soil tester unless there's someone on here familiar with them that says otherwise I think they lie.. and have left me scratching my head in wonder
This one is really cheap but also capable of being calibrated, if you are looking for a cheap but accurate one i would highly recommend this. The only downside is that you have to buy the calibration solution separately.