Baltic Defense.

My opening repetoire has been working out very well:
Chigorin Defense
Tarrasch Defense
Old Indian
Austrian Defense
Balkan Defense
This gives you a wide variety of openings for every situation and every opponent. :)

Are we going for some sort of record for most thread necros in the same thread after gaps of more than a year?
The funny thing is I've actually started considering going back to the Baltic, but as MindBoggle suggested (5 years ago!), only if white doesn't play 2. c4. It just seems like 1. d4 d5 2. Nf3 Bf5 is a decent anti-Colle line.
Against 2. c4, I'm finally getting around to trying the mainstream Queen's Gambit Declined for the first time since I was a beginner. I think it'll be educational. It's just an important enough opening that everyone should play it at some point, just to learn about the game.

This opening is doing ok actually The Liberated Bishop Defence Alexey Bezgodov and there are some youtube videos too.

By the way...
You write that 2...Bf5 messes up Colle players. That will be after 1.d4,d5 2.Nf3 as Colle players don't play 2.c4.
What about playing the Baltic after 1.d4,d5 2.Nf3, you ask?
After the somewhat timid 2.Nf3 black has more options, and 2.Bf5 is one of them, as white, in this case, cannot play the best line (2.c4xd5!). White should never the less reply 3.c4, transposing into a less critical line of the Baltic. After 3...e6 4.Qb3 white gets good play (if he knows how!), but black gets a playable position - albeit somewhat worse than what he gets in the main lines of the queens gambit.
In short: After 2.Nf3 the Baltic is playable, but still slightly dubious.
But the Baltic proper, 1.d4,d5 2.c4!,Bf5?! is definitely dubious - in fact almost unplayable for black - as he will have to accept a very bad position if white knows just one relatively simple line.
It may not be completely lost, especially if black, like my friend, has analyzed the position thoroughly and knows how to give white the hardest problems to solve.
But why insist on suffering in this line when we can just play something else in move 2?
With the great evolution of the engines, several openings and defenses have changed their status drastically. Apos 1. Nf3 d5 2. d4 Bf5! is extremely solid for Blacks. After 3.c4 and e6 White has two great alternatives: Qb3 or Nc3 and both lead to a safe game for Black.
I always start my games with 1. Nf3 and I am very difficult in breaking the solidity of the Black army. I've analyzed the position even more than the 15th bid with the Stockfish 10, but the verdict is one, the Blacks are safe and this is annoying.