CBB13 was close to perfect for me - the only thing letting it down was the repulsive winner.
CBB15 had an amazing first week, but the second half was just repetitive, constant screaming matches between two awful housemates. However, it had a brilliant winner.
CBB17 started off well and peaked in the 2nd week but after Megan's eviction, it became repetitive like CBB15 and I found it quite dull and hard to keep up with. I felt like I was tuning into the same thing every night. I thought the series was a week too long and the awful Steremy showmance dominated too much of the series and even post-series.