A sweather. I also love crochet 
I also knit with needles (mainly thick wools, because it takes shorter time) and embroider (it’s this how it’s called? cross stitches etc., don’t know if I used correct English) and plenty of other “handmade” stuff, but recently I just use this knitting machine because I’m beginning to have the carpal tunnel, hands hurt a lot after a few crochet.
Well it depends on what mistake it is, if you made a mistake a few rows ago, you need to undo the rows and that’s equally hard as with needles. I usually use needles to undo and then put it back to the machine, because I always miss something and then find out after a long looong work 
If you made a mistake somewhere in the current row it’s usually not hard. If you’re doing a pattern, it depends on how complicated it is. I’m doing somewhat harder right know, many adding and removing, but I enjoy it nevertheless I’ll post a photo when it’s done
While listening to this: