I know the player types and styles are different, but I've had 2 AG6 players in my BB "career", and both were great, one better than the other because of when I got them.
I had a wood elf catcher whose first two rolls were +AG. So I was able to build the player with that knowledge. She ended up 8268 catch dodge passblock leap pro (movement downgrade from injury, and that was back when magic helmet was a permanent armor upgrade). Best player I ever had. She only ever had 3 interceptions, because people quickly caught on that if she was on the field, it's best to just not throw passes at all. But that played into the hands of the rest of my team.
Anyway, the 2nd was a dark elf blitzer, he was 7368 block dodge dauntless leap. His +AG rolls were the 2nd and 4th upgrade, so I couldn't plan around those as well. I was able to finally get leap in there though.
The question you have to ask is how many more rolls can you reasonably expect this guy to have? Getting block, as you said, would help keep him alive considerably more than more AG, but the AG+ would certainly be fun and allow you to really cause havoc with your opponents plans. If you think you can get to block later, then go for it.
And as Landrover says, those plays are really memorable. That wood elf catcher was my best player ever, on a team I played with in early vanilla 3rd ed, so probably a solid 14-15 yrs ago, and I still talk about her, and some of my friends still remember her.