Hmmm, I'd say Hoenns actually the best region for area design and pokemon design, even if the plot is appalling ('I don't understand. How can water be good.') and the pokemon are useless (Mawile, Kecleon, Glalie, Tropius: Amazing design, rubbish at battling).
Every region has it's upsides and downsides (Sinnoh improved battling the most, but had the worst pokemon designs, Unova has the best story, but probably the worst post game, Johto has the best post game but it's quite weak in a lot of places and Kanto didn't do anything brilliantly, but was the base upon which all of Pokemon is built).
I certainly wouldn't call Gen 3 the worst.