An interactive catalog of GW detections is available in the GWOSC Event Portal. This is a great way to see how many compact mergers LIGO has observed. What’s the biggest? What’s the smallest?
You can see there are 93 “confident” detections to date. Also, you can sort the columns by total mass, to see:
The largest mass mergers are GW190521 and GW190426_190642. GW190426_190642 is bigger, but its also a marginal detection, and might not be real.
The smallest mergers are two binary neutron star mergers, GW170817 and GW190425.
There’s also a great online plotting tool to see visualizations of this information, created by scientists at Cardiff.