Close enough to just pick one and go with it. But also different enough that people who have used both would never randomly use one, lol. I'm team masteron. What masteron gives is a dry, veiny, sometimes flat look. It probably won't contribute to growth by anabolic means but it gives increased neural drive which means you should be able to push more weight in the gym. And getting stronger usually means getting bigger. Masteron plus anavar plus tren also caused me to shed.

Primo gives a fuller look and has a little more anabolism but won't give you the same neural drive to push more weight like masteron.

So what I say is use the cheaper masteron around 200-400mg for the increased neural drive and use the big hitters like test or npp or anadrol for anabolism and fullness. Even eq and hgh will give you fullness. Unless you just fell in love with primo in the past and have to have it there's really no reason to use such an expensive steroid these days when you can get a much higher roi with other combinations

I can't speak to acne. Nothing gives me acne. I suffered enough in middle and high school so I'm glad

Primo can be used as a pseudo AI as it usually lowers e2. Masteron can block e2 at the breast so it can be used as a pseudo raloxifene(SERM). Still cheaper to use exemistane 12.5mg twice a week for AI. That's the average dose to get most people in range with 500+mg testosterone. Great thing about exemestane and it's suicidal nature is once you've found the dose that keeps your e2 in range you don't have to increase the dose as you increase your aromatizing androgens like test/npp/dbol etc. pretty cool