I think everyone is expecting me to come in here and ram on about Triple H and sleeping his way to the top. I'm not. In fact, the two are more alike then they are dissimilar.
When it comes to power, Lesnar gets the nod. Dude was 6'4" and billed at 295, that's 30 pounds more of muscle for the Next Big Thing. Speed, again, I think anything Triple H could do physically, Lesnar could pull off better.
Triple H simply loses to guys that are built like Lesnar. Batista... a poor man's Brock Lesnar, simply dominated Triple H in their feud in 2005. Batista is the same type of wrestler Lesnar is, minus the talent and ability. Look at the Ultimate Warrior, steam rolled Triple H in no time at Wrestlemania. And yes, that damn Goldberg beat Triple H as well, but since he beat Lesnar, that's a mute point.
Looking back at the time Lesnar was in the WWE, Lesnar was the man on Smackdown. Triple H was the man on Raw. In fact, I would venture to say that Triple H's prime was from his heel turn in 2002 until the time Cena came to Raw in 2005. Lesnar had one less year, but whatever. During that time, Triple H beat the likes of Shawn Michaels, Booker T., Scott Steiner, Kevin Nash... etc. Lesnar was beating guys like The Undertaker, Big Show, Chris Benoit, and Kurt Angle. Both are impressive list, filled with former champions.
If you pay attention to the WWE, it was clearly building up to the Lesnar vs. Triple H match with both guys dominating their brands. This was the rumored main event of Mania 21, but we never got to it.
I prefer Brock Lesnar to Triple H, because I like his style more. However, if you keep it Kayfabe, Triple H has a huge resume as well. I'll probably respond more once Dave gives me something to work with.
Oh and before anyone brings up the disrespected the business bullshit argument at Wrestlemania 20, I'm pretty sure if you remember back to, oh 1996, that Triple H did the same thing, in MSG with the Kliq incident. It's a stupid argument, and save it because no one wants to hear it.