Third choice should be BOTH. We should use what we have, find more when we can, but bear in mind that there is no guarantee that the fossil fuels will be around forever.
There are no viable alternative energy systems in our near future, not even our distant future. Maybe for our grandchildren. GM recalled all their electric cars because there is not enough support to maintain them. The $$$ spent on that project is horrendous, and it solved nothing, just showed that anything is possible if you throw enough money at it. We can't be throwing money away. Continue the research, and hopefully there will be breakthroughs, but don't count on it too soon.
The only thing that CAN be done, now, and cheaply, is to conserve our energy by using less of what we have, and building better houses, lighter cars, mass transportation in areas that have a high density population, and make less trips to the stores for things we really don't need right this very moment. That means lifestyle changes, and after the most recent events, we may be ready to accept that.