Curious on what everyone uses for pump primers, right now we are using Fritz Slick Pack but am always browsing for more options. We've tried using other brands, but just don't seem to get the slickness that we would like. We will not water prime, in my opinion, that is ridiculous, call me whatever, but that's just asking for trouble.

Dirt

I mix a 5 gallon bucket with about 4 gallons of dirt, add water and use a drill with paddle mixer making it a pancake batter consistency. I put 5 gallons of water ahead of it in my system( no Rabbit) add dirt slurry to my stand pipe/prime port, I set up pump in reverse with one piston at the back of the hopper, NO WATER in the hopper, only slight mist, throw it in forward and let it go.. Have primed as much as 300 feet of rock with 3 inch line.( depends on mix) I primed 1050 feet 200 feet head with pea gravel using same method.

Grout is the best but if you can't get grout, dirt at the right consistency will work, betonite works, soap and water or pig your line with a bunch or crumpled up newspaper.

Water+cement is by far the best but not so practical..

My luck with Portland has been mixed.I find the fines being left behind, until I ultimately jam with a rock pack. I have heard but not verified that SpecMix (for mortaring block) is the best. It has powdered fines and sand. In my head it makes perfect sense.

I run  3" system on a trailer pump. Mostly 3/4" stone. I have tried all of the slick packs made. Tried betonite and got tired of the customers worrying about it getting into the pour. I've been using masonry cement mix from Home Depot for the last five  years or so and it's been working great. One bag mixed into pancake batter consistency poured into the hose with out a pig ahead of concrete and it works everytime. Crete  

Builders sand. Runny pasteconsistency. 1 bucket per 50m of 4inch pipeline. Cheap and easy. 

Bentonite. 50# bags for $8 usd cheap and effective. 2.5 cups per 5 gallons of water. I use it everyday average job is 200' of 2.5" hose. I don't use a paddle mixer just high pressure water off the mixer truck when it arrives and spin it around until I have a lumpy pancake batter consistency. I've used the slick pack it works great but it's expensive compared to bentonite 

I really like using Super Primer. Works really good and the cost is wonderful. They have always shipped out really fast to me. Here is there website if you want to check them out.

http://www.superprimer.com/home/

we use a polymer product for all booms and line pumps up to 150 ft. , but the best by far I have ever used is bags of gypsum , I was doing walkways inside of apartment buildings and they couldn't get rid of a bunch of grout , I had a 38z with 225 ft of 2 1/2" line use two twenty pound bags with about ten gallons of water , did this for about 5 pours , never once did the pumps pressure go up or ever think about plugging , but it was kind of messy but effective.

never tried gypsum but I would imagine its like lime that I use because its easier to handle than cement and the hydration will not change much.