I went with 15% up front to match the back. I love it MOST of the time. It’s rough when backing a trailer in the dark, even with auxiliary lighting. I usually roll down my windows, but don’t during mosquito season. Slow and steady!
I try not to bring attention to myself on the road, so I’m not too concerned with the law enforcement issue.
Like everything, it’s a balance.
I know this is a highly debated topic, but I also tinted the windshield 50%. I really really like the windshield tint, but I also understand why it’s such a hot button for others. I haven’t experienced any issues with visibility, but 99% of my driving is on well-lit roads or highways.