We can argue whether Lewandowski is the best or worst striker ever, it's always subjective opinions. Everyone pays attention to different things. I prefer a striker who scores the key goals in 3 out of 10 games rather than one who scores 5 goals in 1 game against an outsider and 0 in the next 9. To consider only goals in the CL as a criterion is an abstraction. Then we leave out strikers such as Van Basten, Batistuta or Lineker. They all were a class better than Lewa.
Is Lewadowski the most expensive Barca player in recent times? Let's check it out! Often Dembele's name is floated on the forum as the biggest misfire. Let's compare which of them 1 point costs Barca more.
Dembele
185 all official games, 40 goals, 42 assists, 82 g+a
bought 135M, sold 50M, loss 85M
salaries: 5x 12M + 1x 16M
total cost: 161M
1 point = 161M/82 = 1.96M
Lewa
66 games, 42 goals, 12 assists, 54 g+a
bought 45M, sold 0, loss 45M
salaries: 1x 20.83M + 3x 26.04M
total cost: 143.95M
1 point = 143.95M/54 = 2.67M
If Lewa will play for Barca until the end of his contract and leaves for free, he will need get 20 points (74+ total) to make 1 of his points cost less than Dembele.
All data from TM, opta, capology.com. Transfer to the Saudi Pro League or MLS will completely change this calculation. Personally I don't believe in Saudi Arabia: 1) Lewa doesn't want to go there, 2) the Sheikhs are rich but not stupid.