There are several choices to be made in adopting a cat.

Whether to choose a kitten or adult is the number one question?

Kittens are one of the cutest things in the world, but just like puppies they normally require a great amount of work. Time needs to be spent cleaning up after the kitten, playing with the kitten and trying to teach it not to claw your furniture. I think you can deter them from clawing but it is something you will always have to stay on top of despite how many scratching posts and the like you have unless you declaw.  If you choose to declaw please only declaw the front paws.  Have you ever had an itch you could not scratch?  By declawing back paws the cat would live its’ entire life with that kind of itch.  Kittens also play with everything and chew on anything, so kitten proofing your house is a must.  Make sure to tie up blinds strings, any kind of cords that hang down.  Kittens have been known to pull things down on top of them. There is not much to do with regards to training.  I have always found the mother teaches them where to go.  If not, I have always, literally, plopped them in the litter box and there they went.  You can try to teach them some tricks, but I find they are very self motivated.
Adult cats are easier in some ways, but harder in others. They are normally very willing to be left alone all day and wait for you to return. Many are already litter box trained and know basic house rules. Sometimes they do have some behavioral problems which can be a challenge to correct.  If you have a multi cat house a new adult cat may spray in order to assert their belonging in the colony.

Male or Female?

Whether you choose a male or female, I recommend to neuter/spay as soon as possible even if they are remaining inside as male cats will mark and spray and females will go into heat.  They will do everything possible to get out the door in order to find a mate. Cats reproduce much faster than dogs. Male cats have a need to defend their territory and to find females. Both pursuits cause them to leave your property. While away they could get into fights with other cats, hit by a car or attacked by dogs. If your pet is neutered he will not be contributing to cat overpopulation while having a walk and will be less likely to leave your property.  I have had cats all my life, indoor and outdoor, male and female.  In my personal experience I find that female cats are better mousers and males are more playful.  Outdoor male cats will tend to wander and females will stick close to home.

Advantages of spaying and neutering:

Spaying eliminates the possibility of uterine or ovarian cancer.

Spayed and neutered pets live longer, healthier lives.

Spaying before the first heat cycle greatly reduces the chance of breast cancer.

Neutering reduces the incidence of prostate cancer and disorders.

Did you know that there are over 70,000 puppies and kittens born in the US

every single day? That’s 7 times the number of human babies born a day.

A single unspayed female cat, coupled with an un-neutered male, and their offspring, and their offspring’s offspring can result in the birth of 420,000
kittens in just 7 years