Pros and cons depend on your style of husbandry really.
New world tarantulas tend to be friendlier to handling, if that's your thing. Urticating hairs are a nuisance but weak venom is a plus.
Old world species can have nasty venom, not deadly, but some are medically significant. The ability to "teleport" is a constant concern, especially with Pokies. Many of the terrestrials are obligate burrowers and I don't enjoy "pet holes."
Both OW and NW have species with aggressive feeding responses, both also have some incredible color variants and patterns.
Personally, I am a fan of NW T's of the genus Brachypelma and OW T's of the Harpactirinae subfamily.