Vileplume is a Grass & Poison type. It has a Base stat of 480 with good Sp.Atk and decent Def. and Sp.Def. The only thing that Vileplume has that isnt very good is its Speed. Also Vileplume has a pretty good movepool, learning moves that benefits its Sp.Atk.
Victreebel is also a Grass & Poison type and it also has a base stat total of 480. Comparing it with Vileplume, It has good Sp.Atk and Atk but lacks Def. and Sp.Def., so Vileplume may stay in battle longer then Victreebel. But Victreebel has much better speed then Vileplume. Also Victreebel doesnt have much of a good movepool when compared with Vileplume.
Conclusion: Vileplume would be a better option.
Hope I helped :-)