There are 7 European spots. 4 in the Champions League and 3 in the Europa League.
2 Europa League spots are reserved for the winners of the League Cup and FA Cup.
Man City, as League Cup winners, already have a European spot, so if they finish in the top 5 then 6th place will effectively get their spot.
If the FA Cup winners finish in the top 6 then the team that finishes 7th in the league will get that particular European spot.
As it seems likely that Watford, Crystal Palace and (possibly) Everton will finish below us, ideally we want Man Utd or West Ham to win the FA Cup.
Of course, we could finish in 6th spot anyway...