Former England international Rio Ferdinand feels Everton's John Stones should pick Manchester United over Chelsea if the defender prefers more playing time.
Champions Chelsea have had bids for the 21-year-old defender turned down with other clubs, including United, also in the fray, according to British media reports.
"If he goes to Man United, he plays every week so that's the right club for him," former England captain and centreback Ferdinand said.
"If he goes to Chelsea, he's not playing every week. He's at that stage of his development where he wants to play every week.
"If you say to any young footballer to leave a club to sit on the bench, you've got to be a lunatic. You have to be."
Ferdinand believes his former club United need to strengthen their defence.
"I don't think (coach Louis Van Gaal) knows his best defence -- that's a problem in itself," the 36-year-old Ferdinand, who retired at the end of last season, added.
"Part of the reason he doesn't know it is because he hasn't had a chance to watch them all play over a long time -- consistently for 12 or 15 games.
"If you don't get that familiarity between you as defenders, it's difficult to build foundations."