The duo went head-to-head twice last season following the Uruguay international's transfer from Liverpool to Camp Nou, and Ramos has earned Suarez's respect with his no-nonsense style defending.
"He's the toughest defender that I've come up against," Suarez told Mundo Deportivo.
"He's very strong, competitive and has plenty of experience.
"That's one of the reasons why there is added importance on the goal I scored against Real Madrid [during Barcelona's 2-1 victory in March] at Camp Nou."
Suarez netted a hat-trick at the weekend to help Barcelona to a 3-1 win over Eibar, and is pleased with the Catalans' results without the injured Lionel Messi.
He added: "I'm very happy with the goals on Sunday as they helped the team whilst Leo is still out. He's our most important player and it's important to win without him in the side currently.
"Leo is doing fine; he's focusing on his recovery plan and is pleased with how things are going. He's also pleased that the team can still win without him playing."
Suarez's feats at the weekend saw him take his tally to 10 goals in 14 appearances in all competitions this season.