Bayern, who face the La Liga side on Tuesday at home, have the chance to shape the contest in their favour right away in front of around 80 000 fans.
But Barcelona have impressed in the second legs, just like they did against AC Milan coming from 2-0 down to win 4-0 in the second leg and getting a later equaliser at home to draw 1-1 with PSG to win on the away goals rule earlier in the competition.
Van Bommel believes that hosting the second leg at the Nou Camp makes Barcelona favourites overall.
In a chat with the Spanish club's official website, he said: "In such an evenly balanced tie, [playing the return leg in Spain] that could be decisive.
"Barca has a very good team and has appeared in six consecutive semi-finals, which says a lot."
Barcelona have never failed to reach the semi-finals since 2005. Even more impressively they have reached three finals since then and have gone on to lift the trophy on all three occasions.
Van Bommel is confident that Barca can go on to win their fourth Champions League title in seven years but believes Bayern's chances are virtually equal.
"Whoever wins the tie will be champions," he predicted.
The winning side will face either Real Madrid or Borussia Dortmund at the Wembley Stadium Final on May 25 - and while many are relishing the possibilities of a Clasico final, Van Bommel thinks otherwise:
"Bayern vs. Barca should have been the Final," he added.