Gers will return to the Scottish Premiership next year after comfortably winning the Championship this term.
The Ibrox side have been impressive under Mark Warburton, and many re already suggesting they could fight for the title next season after defeating rivals Celtic in their recent Scottish Cup semi-final.
Departing boss Deila, however, feels Aberdeen are the more likely to prevent Celtic from winning a sixth straight Premiership title when asked to give his opinion on next season’s likely challengers.
“I think it’s going to be close. I think Aberdeen if they can keep their consistency will be even better, if they can get more experience and maybe get another couple of players as well,” Deila told the Evening Times.
“It’s important that Celtic improves into next season as well. If not, they could be closer. But Celtic are the best team, now, and they have advantages over the other teams when next season starts.”
The Bhoys will no doubt be wary of Aberdeen’s increasing progress in recent years, yet most supporters will acknowledge Old Firm rivals Rangers as the most likely to fight for the title.
The Ibrox club could be able to attract a better standard of player should they win the Scottish Cup and thus qualify for the Europa League, while boss Warburton’s reputation is growing by the week.
Celtic’s current quality within their squad will undoubtedly make them favourites at present, yet the gap between them and the rest isn’t as wide as before which only makes for a healthier top-flight.