As a former Technical Writer (wrote manuals for software and hardware industries), I've done and surveys on readability tests and
Times New Roman 12 point is most preferred by Administators, Managers and technical audiences.
Not that it means too much, but I've never seen Senatorial as part of any font package within MS Word. In fact, I've never seen Senatorial font.
Arial font 10-12 point, is more often used best in Tables, Procedures and captions for illustrations and figures.