If you look at which is going to help humanity more:
1. Electric cars should eventually replace gasoline-powered cars, thus reducing energy usage and pollution. They are also more reliable, so if the high costs of electric vs gasoline are overcome by the industry (ICE cars have been refined and mass-produced over many years vs electric), they should cost less in the end. Lastly, they're safer, again because they're more reliable. I'm only worried about ICE cars dying off because they're way more fun. Same with self-driving cars; I acknowledge that they're better, but there is definitely culture to be lost.
2. Smartphones are useful for communication... which dumbphones could already do. They don't really replace what a PC can do for creation. They just make apps of all sorts more accessible to people. I would argue that they cause more harm than good in the end since so many adults and most of the kids get addicted to using them for silly purposes, and people use them while driving. I often wish they never existed as I get stuck behind some idiot stopped at a green light or see my friend glued to an iPhone screen instead of talking to me. And all Apple does is improve the user experience of smartphones over the years. An iPhone 4 or some crap Samsung phone from 2010 would have been good enough for all utility purposes, and the new "health" features are all bogus. Meanwhile, Tesla tries to improve car technology, which actually means something in real life.
