Magix Soundpools feature a massive quantity of straight WAV files (no Acidization, REX, or Apple Loops). Most loops are short—one to four measures— and this one has a potpourri of styles, including Ambient, Chill, Disco/House, Flamenco (!), Hip Hop, Latin, Minimal Electro, Movie Score (orchestral), R&B Soul, Rock Alternative, and Techno Trance (there’s a demo file for each genre). File names don’t indicate key or tempo, but everything’s in C or Am; if you want to combine flamenco with hip-hop and chill, they’ll almost certainly fit together.
As to instruments, there are drums, guitars, synths, strings, bass, vocals, fx, brass, and keyboards, with hundreds of loops per category (and 1000+ for drums and synths). That’s a lot of material, and the recording quality is far superior to what you might expect, given the low cost.
Magix Soundpools have been a guilty pleasure of mine for years. I even put together an entire movie soundtrack with nothing but the files from one of their sound collections (don’t tell anyone, okay?). There’s so much diversity of material you can create some pretty cool pieces just by pulling various files together and seeing what happens. Yes, manual labor is required if you want to stretch them, but Soundpools are sort of like the audio equivalent of gourmet fast food—and you can’t beat the value.