*G flying J class from EU to SIN in early April. I'm trying to decide which of the following 3 gateways to depart from - CDG (SQ333), FRA (SQ25), or LHR(SQ317). Does the gateway impact my overall flight experience with SQ? If so, which of the 3 would you recommend?

These flights all depart and arrive about the same time of the day and all use 744s. So I guess considerations include quality of lounge, upgrade possibility, load, flight crew/service, and food.