#1 Neymar Jr.
There aren't many players currently better than Neymar in the world. Having started his career in Santos, Neymar moved to FC Barcelona in 2013, and enjoyed stellar success with them as part of the legendary MSN trio. Despite this, under surprising circumstances, the player moved to Paris Saint-Germain in 2017, for a world record fee of €222 million.
However, it is currently being reported by the BBC that the Brazilian is unhappy at the club, and has stated that "I do not want to play more in PSG". This leaves the door open for Barcelona to swoop in and attempt to sign the player once more - a real possibility since the club's dressing room wants Neymar back.
Neymar's return to the Catalan side would certainly benefit their team as his flashy dribbling skills, technical proficiency, and outstanding vision have been missed greatly by Barca, who have not excelled in Europe since his departure.
One hurdle in a potential transfer however is the financial burden with bringing back Neymar. PSG will demand a high transfer fee for their star player, and the player himself will want large wages - however, if this hurdle is tackled by the Blaugrana, consider Neymar's transfer a done deal.