Glasgow or Strathclyde; surely not a valid question? I would say that unless the course at Strathclyde is particularly appealing to you, it'd have to be Glasgow everytime due to their reputation (both domestic and international) and history.
Rankings, even of subjects, tend to vary widely from one year to another, but reputation takes a long time to build up. Or as they might say; form is temporary, class is permanent (ish!).