The problem with the London System is that it allows the following sequence where Black in practice is winning two to one: 1.d4 d5 2.Nf3 Nf6 3.Bf4 c5 4.e3 Nc6 5.c3 Qb6. If Black doesn't play this way against you, chances are good you might have a level game. Not very ambitious, but if you don't like openings, and most London Systemers by definition don't, it may be good enough for you to give Black equality without a struggle from the opening.
That's why White plays nowadays 2. Bf4 first, so 1.d4 d5 2.Bf4 Nf6 3.e3 c5 4.c3 Nc6 5.Nd2 Qb6 6. Qb3, when the c4 + Bf5 idea doesn't work for Black.
@ComradesMarathon: I would go for the London, as it actually has more venom than most people think. The best source you can get is "Winning With the Modern London System" from GM Sedlak.
The London is positional, though. The Colle is downright aggression from white.
In a contest between "Colle and shoot myself" I'd be reaching for the gun.