Well, technically Windows 2.1 (released May 1988) came before OS/2 1.1 (released October 1988). OS/2 1.0 was text-only. So at least for 5 months in 1998, Windows technically beat OS/2.
And OS/2 1.1 was very similar to Windows 2.1, so it's arguable if it was actually much better.
OS/2 1.2 was a massive leap though, not only beating Microsoft GUI wise by a whole year, they even implemented tons of advanced features that we didn't see until Windows 95.
When I started working at Novell in October 1988, I was on the OS/2 team. The version I installed first was 1.0 so I remember that there was no GUI. A few months later we got the update (1.1) with the GUI.
What I remember the most is that they ordered us memory expansion cards that gave us an extra 4MB of RAM for a total of 5MB. I didn't see the actual invoice, but I remember them telling me that the expansion card cost about $2,000. I try to remember that when I complain about memory DIMMs measuring in the dozens of GB going up a bit in price.
And OS/2 1.1 was very similar to Windows 2.1, so it's arguable if it was actually much better.
OS/2 1.2 was a massive leap though, not only beating Microsoft GUI wise by a whole year, they even implemented tons of advanced features that we didn't see until Windows 95.