Salah picked out Sadio Mane with a brilliant pass to open the scoring and then added a brilliant solo goal to make it 4-0 as Klopp's team handed new Watford boss Claudio Ranieri a resounding defeat in his first game in charge.
"Come on, who is better than him? We don't have to talk about what Messi and Ronaldo have done for world football and their dominance, but right now, he is the best," a delighted Klopp told BT Sport.
"His (Salah's) performance was massive today. The pass for the first goal was great, and the second goal was special. He is top. We all see it," he added.
Many in Klopp's star-studded squad were away on international duty, but they slotted back into their club side quickly as they set about demolishing Watford.
"After the international break it is hard to find the rhythm after playing different systems, but the boys were so good despite only having one session before today," Klopp explained.
"I think Watford had ideas, but we didn't let them play. The goals were really brilliant, there was great attitude, energy and character."
Former Chelsea and Leicester City boss Ranieri endured a tough afternoon on his return to English football as his side were completely outplayed in the first half, and they only began to string some passes together when they were 4-0 down.
"I think that we conceded too many chances to them. Of course, Liverpool is a very fantastic team. When I came I knew I would have to work very, very hard ... but I'm sure we can improve. We have to improve," Ranieri told BT Sport.