The best first aircraft will have a cost which does not exceed 2/3 of your budget for the first year, so that you have money to operate it for that first year. If you buy with all your money, you won't be able to operate it. Although I'm not making any negative statement about non certified aircraft, if you learned on a certified aircraft, you might have become used to the benign (and admittedly lackluster and expensive) characteristics. Certainly newer pilots can do well with non certified types, but it takes a more broad set of piloting skills and mentoring.
A C of A aircraft will also be at a known maintenance condition, which will be well documented (and accordingly priced). A non certified aircraft may impose a greater burden upon you to make a determination as to its maintenance status. You'd best be familiar with what you're looking at.
Non certified aircraft might not have some of the "nanny safe" characteristics required for certification. Just make sure your decision in that regard is well informed.
Best to ride in a number to types before you decide. Hang around the flying club, and chat up owners of other types for their thoughts (Note that every owner thinks their aircraft type is best for you!). OFFER TO BUY FUEL for a flight that they might offer to you - it will be worth it!
And then, as well said, consider your most common mission type. Remember, even though you own, you can still rent, if you need four fast seats for the occasional long trip. You don't have to have a larger, faster plane for evening bimbles with your significant other....