That would have been the British. Specifically Churchill & his CIGS Brooke. At the November 1943 Terhan conference Churchill, using info provided by Brooke, tried to persuade the cominded Alled leaders there operations in Italy, the Balkans, and elsewhere would be more productive than in France. He claimed the US, French, and Commonwealth armies would be stalled on the edge of France for a year or more, or possibly defeated. Easy victories were to be had in the mountains of Italy, Greece, Serbia, Norway, ect... in Churchills argument.
Stalin and Roosevelt were having none of it. In the first main conference, after a hour or two of letting Churchill talk Stalin cut him off with a veiled ultimatum. when Churchill attempted to argue on Roosevelt cut in as well, making it crystal clear the US was invading France & marching straight to Germany in 1944, with or without Churchills permission. Brooke, who had also offered alternatives in the preliminary meetings of the staff group saw which way the wind blew and more or less shut up, leaving Chuchill alone at the table. Roosevelt & his Chief of Staff Marshall offered a nominal date of 1 May 1944 as target for a invasion of France and named Eisenhower as the future commander. This along with some other points satisfied Stalin. Churchills staff offered nothing of substance against this, and tho Churchill made attempts to change the decision during the remainder of the conference it was clear to observes and post war historians his ideas no longer counted in this decision.
Churchill did continue efforts after the Terhan conference. On the way back to Britain he stopped at Alexanders HQ and began pressure on him to execute the SHINGLE Operation, @ Anzio. Later he opposed by every means the ANVIL and DRAGOON operations. He made claims the invasion of south France would be utter disaster and probably fail. At best with less success than the Anzio lodgment. He and Brooke managed to keep all but token Commonwealth forces out of Op DRAGOON. Only a Commando and Para brigades participated. Ironically this US/French operation was one of the most successful Allied invasions.
What happens if Churchills view prevailed? The usual consensus is the Read army reaches the Rhine before the west Allies can successfully get a army ashore. Europe is Soviet dominated at least to the Rhine and perhaps France too. Maybe Just Norway, Sweden, Italy and Iberia remain free of the Red Army. Alternately some think the Germans can delay the Red Army east of Poland into 1945 or 46 absent a Allied invasion of France.