I went through a series of Canon point-n-shoots. Each slightly better than the previous, and only upgraded as a camera would break (or get lost).
Eventually I decided to really upgrade, partly by moving to a bigger sensor, mostly by adding dual strobes. I had been shooting with the pop-up flash through a diffuser. I bought an RX100 II, Nauticam rig, dual YS-D1's, a focus light, a wet dome wide lens and a wet macro lens.
I used it for a year, primarily because of the flash. Finally I could reasonably light many subjects.
Problem was, it was still a point-n-shoot when it came to autofocus, and Sony menus just are painful. Basically it was a slow and frustrating camera in use.
At least I had the strobes, arms and focus light now. So I finally bit the bullet and bought a real (expensive) Nauticam housing and ports for my Nikon D810. I opted for the vacuum leak detector for peace of mind. I added a high eyepoint viewer, and bought a 230mm dome port for my 16-35vr, and a macro port for my 105vr.
I've been using this rig for 3 years now, and in the water it's a joy to use, if limited. (No normal zoom lens, so it's either really wide, or macro for me). Out of the water, it's a logistical nightmare of weight and packing limitations. It's 31 pounds to carry to/from the water. But at least I have fast, accurate autofocus. Also amazing dynamic range, and wonderful amounts of resolution for cropping.