The prosthetics and packers that are meant to be glued to the body directly (and not just worn in a harness) are all more expensive than the cheaper kinds. I have heard complaints about almost every single one (lola jake, like real, ftm prosthetics) because they are too heavy, too big, or not realistic or the adhesive doesn't work.
Also, you need to figure out what kind of STP device you can use first, rather than buying a more expensive prosthetic that has an stp option and hoping that it works for you. Not everyone has the same level of success with different kinds of STPs. First, figure out how it works for you (e.g. medicine spoon or other device). THEN see which prosthetics can incorporate that.
I am unaware of ANY prosthetic that has gotten good reviews for being worn with adhesive AND has a good STP.
Last, if your problem is the packer falling out, then you may just need better harness or underwear pouch. I find that sometimes a jockstrap can be more comfortable than the one elastic band style of harness.