It depends on the dish but -- seitan, tempeh, vegan meats, beans! The options are endless!
Tofu's texture is a little questionable for some. Or, is it the fact that it can be semi tasteless? Have you tried certain flavors and different methods of cooking it? If not, I would really suggest it!
Otherwise, the suggestions webmisstress has given you above will work wonderfully! I'd also like to add sweet potatoes. I know it may sound strange. But, they work well in just about anything! And...they are an extremelllllly beneficial and healthy super food.
Happy munching :)