A few things you should do is find someone who has the pistol you would like to purchase, or go to a range that allows you can shoot a variety and try them all. Second you said you wanted to compete (IPSC or IDPA?) make sure it is on the sports approved list or money wasted.
I have shot many types of weapons and a variety of calibers. Some of the guns mentioned above are not cheap. Also take into consideration the accessories you require to purchase as well to compete.
Not all weapons will fit in in different peoples hand and you said your wife was interested in shooting the pistol as well, I like M&P due to the fact that you can change the back strap (other weapons available to do this as well) and they can be purchased everywhere. Before we start a debate on I like this better, it will be you and your wife who will be shooting so get something that fits both your hands (I have shot and owned a variety of pistols M&P, CZ 75, Tarsus .357, Browning 9mm mil issue, Sig 226/225 9mm mil issue not including rifles as well) it is a costly sport . The most important thing is proper hand placement/grip and if the pistol does not fit your hand you will have a hard time mastering the sport and you will get frustrated.
Types of actions, striker fired, single action, single action/double action, double action only. Safety or no safety, de cocking leaver etc. Take all items into consideration and be comfortable and confident with your choice.
9mm is cheaper and popular in the sporting community as an entry gun. Some guns you can by a .40 calibre and for cost effectiveness just buy a conversion kit (check youtube out). .22 is great for target practice, cheap on the wallet as well, keep in mind you will still need to practice a lot with the calibre you choose to be proficient with recoil. Later on when the bug hits you and your wife, other calibers will enter the picture then you will have to think about reloading (this is another discussion).
Cost: keep it cheap (within you budget) for now and practice, save up to buy the Gucci weapon later or modify the one you have. I do not have an unlimited budget so I drool and save to buy the next weapon, collection still growing after 30+ years (wife and 2 kids shoot as well and have their own guns). A good reliable weapon is about $500-700 (Glock, Norenco and M&P to name a couple) you will want extra mags get a range kit that comes with extra mags and the basic items you need to compete (holster, mag carriers, mine came with 5 mags). You can buy some of the pistols above for $1200-3500 in a large calibre and then you will not have the money to go the range and enjoy the sport.
Good luck with choosing the right Pistol for you and your wife.