Hi Jenna,
If you want no loss in sound quality, you need to export in a 'lossless' format such as .wav
Sound cloud itself adds some compression when uploading so you may notice a slight difference in the sound because of this, but at least the actual file you're uploading will be the same as in you're daw so you shouldn't notice too big a difference.
It will be a much larger file than an MP3 and will take longer to upload.
Yodasdad