M class stars
First there are roughly 10x the M type stars than G type. Lotsa chances for planets. Secondly, M stars are stable for TENS of billions of years. One problem with Earth is that the sun will gradually warm and overheat the Earth within a few hundred million years (estimates vary). Bummer, cause it took nearly 4 BILLION years for complex animal life to arise here (are we the retards of the galaxy?). M stars offer chances and chances for life to become complex over tens of billions of years.