You sure want a Buoyancy Compensator Device that can give you more freedom of movement underwater. A BC that holds your tank well while you are in the submerged environment is a great plus. Having a quality and high-performing BC could not be assured when you go for rentals. If you want a BC that fits you well and can give you the perfect buoyancy you want, better research and purchase your own.
Getting an intuitive dive computer these days is not an option anymore, but rather a necessity. Jurassic dive tables are long gone. If you want to ensure a successful and accurate dive, purchasing a dive computer that suits your diving lifestyle is a huge leap to your diving pursuits.
Yes, regulators are heavy and relatively pricey — but if you are someone who dives regularly, it is surely an awesome investment. Having your own regulator will guarantee its good maintenance and performance.