Celtic Manager Neil Lennon has his side's Champions League draw alongside Barcelona, AC Milan and Ajax is "the best and the worst draw" they could have had.
The draws for Arsenal and Celtic were the most eye-catching of those handed to the British sides.
Scottish champions Celtic clinched their place in the draw after a dramatic play-off comeback against Shakhter Karagandy.
Neil Lennon’s side memorably beat Barca at Parkhead in last season’s group stage last November with a dramatic late goal from Tony Watt.
Milan and Ajax add further glamour to the group. The four clubs between them have won 16 European titles.
Lennon told Sky Sports News: ``I think it is the best and the worst draw we could have got.
“In terms of glamour I don’t think it comes any better than Barcelona, Ajax and AC Milan.
“In terms of football it is probably the most difficult group we could have got.
“But I think the hard work was really done last night and we can go and enjoy the tournament now.”
Arsenal, who have reached this stage of the competition for 16 successive seasons, also played Dortmund in their group two years ago.
On that occasion Dortmund finished bottom of the section but the Germans are now a much tougher proposition and impressed throughout their run to the final last year.
Napoli, where Benitez took charge after leaving Chelsea last summer, were the side in pot four most clubs wanted to avoid.
After tough draws and disappointing group stage exits in each of the last two seasons, City had feared another hard set of fixtures.
But although they must take on Munich again, they may be relieved to be facing two of the continent’s lesser lights in CSKA and Czech side Viktoria Plzen.
New manager Manuel Pellegrini has taken both Villarreal and Malaga to the latter stages of the competition and there would be disappointment if City failed to reach the knockout rounds again.
City captain Vincent Kompany tweeted: “Interesting draw. Big year for us.”
For United and Chelsea, the tasks look reasonably straightforward. Moyes will be expected to guide a side that has reached the final three times since 2008 through the likes of Donetsk, Leverkusen and Sociedad.
Jose Mourinho’s Chelsea, the 2012 winners and current holders of the Europa League, will be favourites to top Group E.
UEFA Champions Legaue Group Stage as follow:
Group A Man Utd Shakhtar Donetsk Bayer Leverkusen Real Sociedad
Group B Real Madrid Juventus Galatasaray FC Copenhagen
Group C Benfica PSG Olympiacos Anderlecht
Group D Bayern Munich CSKA Moscow Man City Plzen
Group E Chelsea Schalke 04 BaslePorto Porto Steaua Bucaresti
Group F Arsenal Marseille Borussia Dortmund Napoli
Group G FC Porto Atletico Madrid Zenit St Petersburg FK Austria Vienna
Group H FC Barcelona AC Milan Ajax Celtic