I've sat at Becketts for about the last 5 years, it doesn't really matter where in those stands you are, you will get a great view and an awesome time. I've never sat as far forward as row A, and my preference would always be closer to the action. I like to take photos and having no one in front would be amazing, conversely, I've been there in torrential storms and watched the first 3 rows vacate to get some respite on the stairs, much to the grandstand safety steward's dismay.
I can't remember exactly which end block 3 is at, but I assume it's the last one along the direction of the track, which means visibility of the cars through the Becketts turns will be immense. You might lose a bit of sight of them coming in and leaving, and across to Village/down the Wellington straight, but it'll be marginal and there will be a big screen the other side of the track to keep an eye on action elsewhere.
Enjoy!
