The only thing I can suggest is to take models that have options. For instance, maybe take some squads of Noise Marine 'Havoc's, since you can field some Sonic Blasters and Blastmasters together, and with their varying weapon frequencies, the guns can do double duty. You can also take a bunch of Obliterators, because their weapons will always be helpful.
The other option is to just say 'frak everyone else' and make the army list YOU want. My main army right now is 2000 points of Thousand Sons. Yes, I have about 3k worth of models and units, but I have a 'primary line' that I keep for my own preferences and tastes, and you just use it. Let other people adapt to you, instead of you to them. For instance; I hate worrying about heavy armor in my lists, and so if my opponent breaks out a ton of Lascannons, I can smile and watch them bitch that each shot is wasted on a single Rubric Marine.
The other option is to just say 'frak everyone else' and make the army list YOU want. My main army right now is 2000 points of Thousand Sons. Yes, I have about 3k worth of models and units, but I have a 'primary line' that I keep for my own preferences and tastes, and you just use it. Let other people adapt to you, instead of you to them. For instance; I hate worrying about heavy armor in my lists, and so if my opponent breaks out a ton of Lascannons, I can smile and watch them bitch that each shot is wasted on a single Rubric Marine.