FZONE Pro Series
Great value for money! It's completely modular, which is great for larger CO2 tanks and multiple aquarium setups. It's fairly easy to set up, but it also very bulky.
FZONE Standard Regulator
Cheap entry level single-stage regulator.
FZONE Mini Series V3.0
Paintball Compatible!
CO2Art PRO-SE Series
From a reputable company. This is a great regulator, but it is pricey and has some reports of initial issues.
FZONE Paintball Regulator
Another great value for money regulator! Made specifically for paintball canisters!
JARDLI PRO-E1
Paintball canister adapter included! Great entry regulator! One report of bubble counter not completely watertight.
Clscea CO2 Regulator
Interesting assembly design. Do need of wrenches or other tools. Not sure if you can call this modular or not as you can easily replace the solenoid bubble counter. Clscea is also an unknown brand.
Full Transparency: I have not used this regulator before. I cannot verify the quality of its intricate design.
ZRDR A:JYF-K303
This is cheap. Too good to be good, cheap. Be aware of that if you decide to purchase this.
ZRDR CO2 Regulator
Another cheap entry regulator. However, I would choose FZONE over ZRDR
ZRDR Compact CO2 Regulator
Just get an FZONE one instead of this… That being said, this is very lightweight and compact.
ZRDR FSQ-Double Meter-BT
For DIY CO2 Generators. My experience has been "eh". I've had inconsistent CO2 output with it.
AQUATEK CGA320 Paintball Adapter
In case you need one.
CARPJZ Refillable Bubble Counter
In case you need it.