I start every year doing a 30 year modern day set up sim. At the end of the sim I only look at teams that have offered me a GM job that year. At that point I look at the team that has been the least successful over the last 30 years with ties taking a look to 40 years back.
I use the 2-8 scale, Low trade / Favor prospects, and draft pool revealed 200 days out. I will also do some sort of divisional realignment as the game will have expanded by two to six teams in the 30 simmed years. That also means setting up a custom playoff, but noting to outlandish. Four Division winners and two, sometimes 3 wildcards.
For years I did the Cubs, but eventually grew frustrated as my Cubs outperformed the real world Cubs every year. Then Theoyer and friends came along and the rest they say is history.