Although not traditionally a DAW, OpenMPT’s currently my main (especially when I use VSTs and soundfonts alongside pure samples for audio rendering duties. Caustic 3, though, that was my first proper DAW, and taught me some basic and advanced techniques in music production, in a fairly-accessible, yet deep-rooted audio-visual interface.
For what it essentially entails, Analog Obsession’s busterSE does quite a bangin’ job at being a analog-style stereo compressor, with the ability to tilt whatever part of the frequency spectrum you wanna have spread out, in spite of its limitations on the surface. Kicks, snares, pads, even the entire mix, you name it.
Of second, yet equal, mention, is ChowDSP’s Chow Tape Model. which I’ve found so far to be both versatile and not that CPU-hungry. not only at those tape-esque warm flavors, but also at aiding modern, multigenre music compositions. I use them both, or either one of them, depending on the situation, and both are forever free high-quality.