Greengold,
I do not have much experience using booster pads with pull-ups, but I have used them for years with my tabbed diapers.
Over time I probably have tried them all and have found NorthShore Care's own booster pads to be the best for my needs. I buy them in multiple sizes so that I can select the exact amount of added absorbency I need for each occasion.
However, I recommend that at first you buy some of the "small" size booster pads as they will give you 15 ounces of absorbency. Size "Medium" will give you 18 ounces of absorbency and "Large" will give you 21 ounces of absorbency. That being said, booster pads are like our diapers. The absorbency in the rear part of our diapers usually is underused. The same is true for booster pads. The rear portion of a medium or large booster pad may go unused. That wastes absorbency - and money. In contrast, a "small" booster pad may be 100% used.
Another consideration is the space between the internal standing leak guards in your diaper. If the booster pad totally fills that space it may prevent urine from effectively reaching the diaper's own very absorbent mat. IMHO, a well-chosen booster pad should leave about 1/2 to 3/4" of space on either side of the booster pad to allow urine to make direct contact with the diaper's absorbent mat. The NorthShore Care diapers have a generous amount of space between the internal standing leak guards. A "medium" booster pad fits there with space to spare. A "large" will fit there but with minimum space left. I should note that I do use size "large" booster pads when I will be away from home and need 6+ hours of absorbency. I will add that, due to my severe chronic constipation, I have to remain well-hydrated and thus the diaper alone will not last long enough. When I teach my afternoon and evening ESL classes I have to allow for travel time + class time. That usually is about 6 1/2 to 7 hours. A large booster pad is very effective in that type of situation.
--John