>>43166793TD isn't really good, but it's still weirdly enjoyable. It perfectly rides that feeling of guilty pleasure.
Seasons 1, 3 and Ridonculous Race are the ones you'd want to watch if you want to keep watching.
RR is basically a spin-off with a different format, comes with its strengths and weaknesses. Season 2 is too slowly paced and only really worth it if you're a big fan of Lindsay and Harold. Season 4 was the start of 13 episode seasons and wacky new cast members instead of exaggerated stereotypes, weak in just about every regard and only saved by the Heather cameo. Season 6 is better than 4, but the elimination order is shit and cucks a lot of the better characters + 13 episode format still sucks. Do not touch Season 5, ever.