It depends on the country
South Africa, Pakistan, New Zealand, West Indies, Bangladesh and Sri Lanka would take a WC. Coz they either haven’t won or it has been a long time since winning
But countries like India and England would take such a challenging back to back test series win
Also it’s not either or.
-Tests show the quality of the team
-ODIs are a good balance between Tests and T20Is, neither longer like tests (most don’t have time to watch tests) nor a tamasha cricket like T20s (which traditionalists won’t like)
-T20Is, IPL and other leagues are necessary for entertainment, sponsors and revenue generation which in turn can be used to invest in the domestic cricket and player development
India is the best country when it comes to cricket. They’re #1 in tests(not just ranking), two 50 over WCs and CTs, a T20I wc and has the IPL