We don’t have much distribution in Cressi near where I live and I have only run into a couple of operators who rented Cressi gear so I can’t speak much from personal experience.
@Damselfish gave great advice and I agree, especially if the OP is not yet certified. I have seen students not make it through certification. That aside and not trying to be a negative Nellie...
I am a strong supporter of getting one’s own gear because of comfort/fit, familiarity, etc. no need to waste time figuring how much weight and where you need it, getting used to the gear, etc., you know when your gear was last serviced and will know how it performs. However, I do believe there is value in using some rentals, speaking to others about the different setups and gear they have, gathering feedback (likes and dislikes, listening to their reflections, regrets, if they did it again thoughts, and then making an informed and educated decision that way. It will decrease the likelihood of having to buy gear again because the trigger was pulled too early.
I learned renting wetsuits that I get cold easily and the standard 3mm rentals in tropical locations were marginally enough so I bought a thicker wetsuit and also opted for a 3mm to use with a vest or hooded vest. Out of the gate, I would have purchased an Aqua Lung BC with i3, but after speaking with folks who used to dive with one and had experienced with it and using an AL rental myself, I changed my mind. The weight pockets drove me crazy. After diving many rental regs, I loved having a venturi lever and realized what the different sizes and weights of a second stage translated to in my mouth. These are just some quick examples of many. So when I was ready to buy my gear, I had an idea of where I was going to start.
Some things to consider are what type of diving and where, how often. As an example, if you only dive on vacations once in a while, it may be difficult to justify the purchase of a reg considering the maintenance costs.