The 33-year-old ex-England international moved to Clermont in 2015, after five years at Saracens.
The defending champions are on track for a successive double as they also look to retain their Premiership title.
"Saracens don't have a bad day, they are consistently good", said Strettle.
"They are for me the number one team in Europe," Strettle told AFP. "However, Clermont's good days are better than Saracens' good days so if we are playing well, we can win."
Clermont are the nearly men of French rugby, having lost to Toulon in Europe's top club tournament in the 2013 and 2015 finals, and won only one of their 12 French finals - and that at the 11th attempt.
"It doesn't affect me if Clermont have won or lost 11, 12 finals," said Strettle, who scored in their 27-22 semi-final win over Leinster.
"That shouldn't affect me, I am playing just the one game, in my head it is the same. The players just have to ignore the history, it's just one game. For the fans, it's different."
Saracens are the "number one team in Europe" but Clermont Auvergne are capable of winning Saturday's European Champions Cup final, says their former winger David Strettle.