This is the most difficult question !!! I love all pets too ; every kind has its own great side !!
But maybe I can tell you why we chose for a cat ???

Well ? I'm not working anymore because I have to much health-problems . Because both our kids are at school all day and my hubby works late always , I decided I needed a companion . I then chose for a kitten . Why ?? Well a cat is very independent and the only thing a cat needs is much love and caring . I mean it is not necessary to go and walk around the block every day . Dogs do need that !!!
So now we have a lovely great purring indoor cat , named Sydney ! He keeps me company all day , gives me so much love that I love him as if he was a child of mine !! The only extra work he gives me is that I have to refresh his litter-box regularly , but that is no hassle !
I hope I helped you with this !!!!

ps. we also have a little bunny Billie , but it's my daughter's pet , so she takes care of it !