I've been using a Meikon housing for my Olympus E-M10 for almost 4 years now. Never had a leak. The only problems I've had with it are:
- it's rated for 132 feet. I dived it to 135 once and several of the buttons were pushed and held in by water pressure, which made my camera not work right. That was about 3 years ago. It has still been fine and never leaked before or since then.
- The button that is used for Back Button Focus has developed a tendency to stick in when I push it. Fortunately, I have always been able to kind of grab it with my fingernails and pull it back out, during the dive.
Really, for what it cost, I'd say my Meikon housing has been amazingly good.
I also started off using the Meikon wide angle dome. That has also worked well. But, a year or so ago, I got a Nauticam WWL-1 wet wide angle dome to use instead of the Meikon. The improvement in image quality is visible to me and to friends of mine who are familiar with my photos from before and now.
Now, I have stepped up to a Sony a7r IV in a Nauticam housing. I'm still using the WWL-1, but it is more limiting when paired with a Sony Full Frame camera. It only works with the Sony 28mm f/2 lens. So, no more ability to zoom in and out, like I had with the Olympus.
@Barmaglot made many good points.
When you total up everything you'll need to spend to take photos underwater with an a7II, you might re-think that whole plan. Also of note is that I think the a7II battery life is not that good. No big deal to change batteries during a land shoot. But, changing batteries while on a boat is kind of risky. The later generations of the a7 have better battery life and don't normally need to be changed during a single day of shooting. But, I think the a7II is likely to need changing during a single day.
If you really want to use the a7II, you'd probably be best off to be patient and look for a used Nauticam, Aquatica, or other more high-end housing.
If you just want to shoot underwater, but don't HAVE to use your a7II, you might consider looking for an a6300 (or 6500) and using a Meikon or SeaFrogs housing for that. Basically, the smaller sensor results in much lower costs downstream (for lenses, ports, etc.). You might be able to get a whole rig, with the camera body, for less total cash outlay than what it will cost you to properly house your a7II.