Well the XAE (xcom armory expanded) mod contains a lot of stuff and works together.
Picking and choosing, I like Modest Rebalance, Equal Terms 1.0, Body Armor, Human Plasma Weapons, and of course the new UFOs/New Terrain mods. I also found one on the forum that reverse the progression of lasers, making heavies a bit more useful, and giving more time for the new human weapons to be used.