Republican presidents tend to be elected during good economic conditions while Democratic presidents tend to be elected during bad economic conditions. The latter has much better growth potential while the former has far higher downside risk.
That's not actually really correct. Reagan and W. Bush were both elected during recessions or downturns in economic growth. Reagan during stagflation and W. Bush right around the time the 'dot.com' bubble burst.
And indeed, Reagan's economic performance
is better than any post-1968 president except Clinton.