I use a harness because I'm allergic to all medical adhesives, even the hypoallergenic adhesives, but the other guys have tried "Reelmagik" "FtmProsthetics" "Emisil" for the more 'natural' sex you are looking for. (no straps or harness) I am forgetting some companies, but other people will mention them soon, I'm sure.
There is a large amount of prosthetic reviews on this forum for the companies I mentioned. Keep searching the ftm gear forum here on Susan's place. It seems a lot of guys have had problems with the medical adhesive staying adhered to the pubic area.
I highly suggest watching youtube videos of prosthetic reviews, but keep in mind that everyone is looking for different things in their prosthetic, it's very personal preference based.