Usually they favor Democrats by a small margin overall. Fivethirtyeight maintains a list and the accuracy.
https://projects.fivethirtyeight.com/pollster-ratings/
Susquehanna Polling & Research Inc.
D+0.9
538 though lists polls by polling firms that hide their sampling percentages from scrutiny so that you can’t rip them when they oversample Dems and undersample Repubs and Indies.