With regard to the housing, I would get a housing that mounts different makes of lens ports. This is because ports can be expensive and one can save money by buying used lens ports and extenders of different makes.
The Isotta housing (as well as similar but more expensive housings) accepts Sea&Sea ports as well as adapters for other makes, and is reasonably priced compared to other housings. For the Sony A7 it is about $2,850. This port versatility may well offset the extra cost compared to Ikelite, which does not conform to international standars, and only mates with Ikelite ports.
Plus the Isotta housing, and similar housings, accepts fiber optic cables, so that one can use a variety of strobes, while with an Ikelite housing one has to use electrically triggered strobes. These factors add up in the long term, as one's requirements change and expand, in favor of an Isotta, or similar, housing.
