I don’t have one Sim that I continuously use over and over again in TS4. Playing the pre-mades repeatedly gets kind of boring for me, and the Sims that I’ve made myself or have come across (such as randomly generated townies); their storylines are too important to me for me to set them in an entirely different save and change.
But TS3 was different. I had a Sim that I’d play with in various saves with various storylines. I named him Hayden Monroe. Beau Merrick was a pre-made that I constantly played with and adored as well. He never ended up with any of the women he lived with though; he typically ended up with Hayden. :D