Good question! The entire BOINC system is based around a work unit. The harder the task, the more points you get. However, I would recommend that you do some easy work for SETI@home. In the project preferences, you can deselect the "Long runs" option and instead choose the "Short runs" option. It doesn't matter which projects you do, but on how much work you've done on it. Choose any project you want, but make sure your device can handle it.