Funny as it seems, Leo, would have done a fabulous job. I saw him inconcert and the guy ran all over the place kicken dancing and jumping. He also did mime. Yeah he would have done just fine.
Of course it doesn't. The thing about Van Halen is kinda like James Bond, I think. The first one that got your attention becomes your favorite. For people that were in from the beginning, Dave will always be the guy. For folks that came on board with Sammy, well, he's your man. I was in high school when 1984 was released, but also when 5150 came out. So I straddle the line as both lineups contributed to the soundtrack of my high school years.
I wouldn't say better, but definitely different. The music was more complex and involved with Sammy, but with Roth Eddie was under constant pressure to stay away from the keyboards and stick with the stunt guitar. Sammy encouraged Eddie to follow his whims and had the range to sing over all of it.
On the flip side, Roth VH was a stripped down, good times party band. There's an undeniable appeal to that, too.
What in the world is more complex about van hagar songs? The lyrics are embarassingly trite, and the riffs and structures are typical van halen, but mellowed out.
Eddie branched out a lot more with the keyboards, so the songs were often not riff based like the majority of the Roth era songs were. This actually started with 1984, which was arguably their "crossover/breakthrough" album, so Eddie was already moving in that direction before Roth left the band.