Reddit reviews HATCH Xtak Knee Pad - Black

It sounds to me like you want to get some kind of construction kneepad since they have a flat front which is better for being on your knees for a long duration vs. "tactical"/military focused kneepads which are designed to stay on well while moving and give protection while transitioning into different firing positions in rough terrain.

Any of the mid priced options here will probably work fine for your purposes, you definitely want something with gel though.
https://www.lowes.com/pl/Knee-pads-Jobsite-safety-Safety/4294644960

As for military knee pads, my personal favorite is the Hatch X-Tak, and I am speaking as someone who has worn them for the past 6 years between being in the military, training after the military, and while hiking to keep my knees from getting wrecked while doing camp chores.

https://www.amazon.com/HATCH-Xtak-Knee-Pad-Black/dp/B01AJ5DNZ4/ref=sr_1_10?s=sporting-goods&ie=UTF8&qid=1480215796&sr=1-10&keywords=hatch+xtak+knee+pads

I figured black would be more your speed, but the OD green is my favorite. Make sure you are getting the knee pads and not the elbow pads.

Anyways, cheers and I hope you find what you are looking for. Remember, soft front pads will wear out faster, but they might be easier to conceal/wear without distracting you with noise, etc.

I just got the Hatch Xtak. Seems nice, though I haven't gotten to use them in a game yet.