This is very true. It also depends on if you have allergies (animals and bedding can cause issues), and what you want out of a pet. I work at a pet store, and have to assess this with people all day long at work.
It's largely about assessing initial cost, long term cost, cleaning, if young kids will be around, allergies, and how often you want to have to play with it.
Some animals can not tolerate young kids, or will easily be injured by them. Some also need attention daily to stay friendly pets. Others you just feed once a week, make sure they have water and heat, and clean cage as needed.

I am allergic to most things with fur, that said I love bearded dragons and chinchillas the most. Little more of an upfront cost, but worth it in the end and they have a good lifespan (dragons 10-15 yrs, chins 15-20yrs). Both very social and love attention, and have cute personalities that differ from one to the next. Bearded dragons are naturally nice, and will still be friendly even if you do not hold them very often (great for if you are busy a lot). Chinchillas also live up in the mountains naturally so no body oil smell like most furry animals, and they produce less waste so little smell there too.

Hope that helps some.