Grilled sloooowly with garlic and onions! Garlic powder is good, but ALWAYS use freshly cut onions. White onions are best IMHO.
Also, get good beef. I used to think any good fresh beef was good. But then I started trying some from a cheap grociery store, they had the cheapest and BEST ground beef I've had. Wal-Mart, Winn Dixie, Abertsons, all had fresh beef, but tasted stale and inferior towards the bargain grociery store. The only thing I did find out is that their beef is never more than a couple hours old from being ground. I don't know if theirs was always fresher or what makes it better, but I am convinced to compare other beef among stores. But I also try to limit the amount of red meat we consume.
Oh, don't bother with liquid smoke on burgers. And if you do, make it extremely small amounts. The biggest mistake is people over doing the liquid smoke. But IMHO it tastes too artificial. I'd rather use wood chips to get the REAL THING by slowly smoking it, oh YES!!!
I think I will smoke some steaks now!