1 & 2 are the only "good" of the series.
The worst: III and specially IV. Unpopular opinion: Saw V is the less bad. The simple cat-and-mouse game and classical traps (pendulum, inclosing walls) was better than the progressively boring and annoying moral disquisitions and multitude character narrative of the others, although the somewhat ¿parodic? tone of VI & VII was more watchable than III & IV.