My 150 -- my 2nd planted tank -- I did with dirt and sand cap. It was amazing growth for the first 3 years. Now, it's exhausted and I'm about ready to give up and tear the whole masterpiece down. Plants just aren't doing as well. I fertilize (water and tabs in the substrate), but it's not helping enough.
Dirted tanks are also MURDER if you like to move plants around. Anytime you haul stuff up from the dirt (roots!), dirt particles end up in the water. Cloudy mess. Drives me insane.
Aquavitro-type substrates are also really nice, but I don't think they 'scape as well. Much harder to make hills and stuff. Also fragile, and you end up with mud pretty easy if you rustle it up. Still, good stuff.
Just my 0.02, crusty old gulo that I am.