Indicia title on #1-93 and #139-141 is 'The X-Men'.
Indicia title on #94-138 is simply 'X-Men'.
Cover title is 'The X-Men' from #1-49 (with additional, larger character or storyline logos on #42-48).
Cover title is 'X-Men' from #50-93 (the last reprint issue).
Cover title is 'The All-New, All-Different X-Men' on #94-99, #101-103, and #105-111.
Cover title is 'The Uncanny X-Men' on #114-136, and #139-141.
Cover title is just 'X-Men' (often to make room for other cover copy) on #100, #104, #112, #113, #137, and #138.