This stadium is awesome for football and there is no bad seat in the place. I like sitting in the second level because the tickets are a little cheaper but you are still pretty close to the action. The Upper deck still has a good vantage point and can usually be bought for around $40.
The stadium is built for the NFL and has many amenities and luxury boxes as well as great Wi-FI for those that need to stay connected. The seating is of course more expensive closer to the stadium but its worth it.
The higher you sit the cheaper it is. This stadium is for the NFL, so the closer the more expensive. But high up you still have a great view of everything that's going on, and the full crowd.
Once inside NRG, typically the best place to view the game is as close to the 50 yard line as possible in the middle tier. This might not always be possible $$$$ so just get as close to the action as you can so you can feel the hits on the field!
1st row 50 yard line are the best, but thats not always possible because of the prices. If not, I'd try to get seats that are above the 50 yard line (middle of field). Around halfway up in the stands but near the 50 will be amazing seats. End zone seats can be cool when the play is in your area, but not so much when it's on the other side.