Yes jelqing up = girth, but makes it a bit smaller, but you will have rock hard erections.
STRAIGHT AHEAD = Length, and girth, but less girth than up, BUT I like this way best after MUCH trial and error over yearsss and years, since I was like 13 or so I've been jelqing on and off, however I do sometimes jelq slightly up a tiny bit, there are it's benefits to jelqing up, like stronger erection and girth.
Downward, as far as I've heard, and also experienced, decreases blood flow and serves me no purpose for length for girth because it makes my erection noticably weaker.