Just wanted to specify that I'm not a dive operator here on Phuket, nor affiliated with any. I've listened to the OP's needs and concluded that the best course of action would be to have someone customizing their diving experience and I have provided them with two choices.The problem with this board is that most of the replies here are coming from Phuket dive operators, which are NOT necessarily the clients' point of view... and it looks like there is a big difference between the way some dive operators and regular clients see Phuket diving.
Maybe sometimes operators should hear what clients say, don't you think?
And to further illustrate my point - the best dive I ever had on Phuket was with South Siam Divers that you've mentioned. I went diving with a group of five of my colleagues - all instructors. We went to King Cruiser, Koh Doc Mai and Shark Point in one day. Except for myself, none of my friends have been diving these sites before. Still, we told South Siam crew we needed no guide and they allowed us to go alone. We've seen lots of things and had lots of fun on these dives. Yet, it was a totally different experience from what the OP asked for and it would make no sense to recommend South Siam based on this experience.
We did give our honest opinions but sometimes "clients" don't seem to listen.
Having said that, if we were to generalize, there would be a lot of truth in your post as well.