Admittedly, I haven't actually been to Universal in about 1 1/2 years but I did work there a few years ago, and for many years (before & after working there) had an annual pass.
I would expect it to be quite busy. School is out and Universal is VERY popular with the middle-high school age local kids. Day tickets & year passes are cheap and Universal is conveniently located along a subway stop, so kids from the Valley to great LA can easily access it. In fact, my 2 younger sisters are actually planning on going 2x this week alone.
This is also a heavy tour-group time of year, particularly foreign tourists, which are mega groups.
As for FoTL passes, I can't give much advice there, as I know there are some new things since I've been last but idk how that's affected the lines.
When I worked there (2006-7), I did not find the FoTL passes a good value but the rides with the longest lines (Mummy & Jurassic Park), never had what I found to be an unbearable wait. This is because there aren't that many rides at Universal to begin with, so to me, the lines aren't a particular grievance.
If the Transformers ride is really pulling in high attendance though (as I'm sure it's line is long, as it's a new ride), it might affect how much you do throughout the day.
Best advice I can offer is to do the Studio Tour early in the morning. I'd say first thing, but maybe if someone else can offer what the Transformers line has been like, then probably do that first. But the tour is a must-see and takes a bit of time, so get it done early.
Have fun!
