Stanadyne has been the preferred and recommended additive around here since it's made by the folks who built the injection pumps. However, it's kind of like asking which engine oil is the best - as long as it meets the requirements of the engine mfg, then it's okay to use. And you'll find as many opinions as there are additives and oils.
Personally, I have used Power Service for 30 years now. It's always treated me well. I actually had problems with gelling when using Howes. Anything that you use that adds lubrication and prevents gelling will be fine.
Casey
1995 K1500 Tahoe 2 door, 6.5LTD, 4L80E, NP241, 3.42's, 285/75R16 BFG K02's; 1997 506 block; Kennedy OPS harness, gauges, Quick Heat plugs, and TD-Max chip; Dtech FSD on FSD Cooler; vacuum pump deleted, HX35 turbo, Turbo Master, 3.5" Kennedy exhaust, F code intake; dual t/stats, HO water pump, Champion radiator; Racor fuel filter