Not discrediting anything what Horry did, but still say Thomas. Guy set an NFL record for sacks in one game that still stands today. He came close to matching his own record with 6 sacks vs Oakland. You just don't see stuff like that anymore. Khalil Mack had 5 sacks the other week, still no one has beaten his record.
Used to be said that the 80s belonged to L.T, but the 90s belonged to D.T. 126.5 sacks all time, 41 forced fumbles, and 642 tackles. His death was unfortunate and cut his career short.
Now, to argue my post, Horry without a doubt is top 10 one of the most clutch performers in NBA history. To go with that, he holds an NBA record for most 3-pointers in the NBA finals. What Horry has over Thomas is a rings- where Horry has 7 NBA championships to Thomas's 0. In terms of success though, I can't see how Horry would be over DT. Thomas is down as one of the most feared defensive players in NFL history, whereas over the course of Horry's career, he averaged just 7 points per game, and 8 in the playoffs.