To add to all this ......... You can also record a mono signal (guitar or vocals) and make it a stereo signal later on. One way to do this is to copy your mono track (track 1) and paste it into empty tracks 2 and 3. Now you have 3 tracks of the same mono signal.
Then you drag track 2 slightly ahead of track 1 and drag track 3 slightly behind track 1. (maybe 15ms each)
Pan tracks 2 and 3 hard left and right (or whatever your ears tell you).
This will give you full, natural stereo chorus type of effect.
There's also the difference between headphones and monitors. Stereo or chorus type processing sounds pleasing in headphones, but warbly in monitors, whereas a mono signal either centered, or panned sounds great on monitors but borring in headphones. Just something to keep in mind.
Many people mix with headphones nowadays and get caught up in too much stereo processing because it sounds better in headphones, but when you play it through monitors, it sounds like crap.