Goff v. Lynch is an interesting debate to me.
It seems from watching them that Goff is significantly more refined and a lot closer to being able to play in the NFL today (although he's not a "plug and play"). While he does run a bit of a gimmicky air raid, you can see Goff go through progressions on most plays and often times find his 3rd or even 4th read.
Another thing I actually kind of like with Goff is that his OL is pretty bad. As weird as that sounds, I don't really want a QB that played his college career always having all day to throw. Goff has essentially had on the job training of how to move around in the pocket and how to hang in there and deliver strikes knowing he's going to take a hit.
There are some negatives to Goff. Just looking at him he appears to be very thin. He's listed 215, but I'm not convinced he's that big. Also, his arm doesn't appear to be all that strong. The ball gets to where it's supposed to be, but it seems to come out wobbly and fluttery way more than you want to see.
I also don't think it's fair to throw this all on him, but the fact is that Goff's performance has been worse against Cal's better competition. His three worst games of the year have all come within the last month, all on the road, and all against Cal's tougher PAC-12 competition.
With Lynch it's all about projectability. He actually is what most people thought Cardale Jones was going be before the year. A huge kid (6'6" 230) with great athleticism for the QB position, a big arm (although not as big as Cardale's so don't think I'm making that comparison) and a ton of production.
Lynch's progressions are, to my untrained eye, simpler than Goff's. He doesn't seem to make more than one read (usually doesn't need to), two at the absolute most. For as big as he is, Lynch doesn't have the monster cannon arm that you would expect, although I'd say his arm is quite a bit better than Goff's in terms of strength/velocity.
One thing that concerns me with Lynch is that he has a bit of a windup. His release isn't what I would call lightning quick, especially compared to Goff who really gets the ball out quick. Another factor to consider is that there have been some whispers that Goff's shoulder might be a medical red flag when it's all said and done. I'd want/need to look into that as closely as possible before picking him.
I think on size and arm strength alone (not to mention athleticism) Lynch has the higher ceiling between he and Goff, but he's a good bit further way from being able to play. I think there's a good chance he would struggle a lot if he was put into action as a rookie (not dissimilar to Blake Bortles). Whereas with Goff, with his current skill set and ability, I think he could step into the McCown version of DeFilippo's offense and run it competently. While any QB can bust, it seems Goff is less likely to be one.
If both are on the board, I'd probably roll the dice and pick Lynch because of the upside, but I'd be fine with either guy.