Try looking at more than just the graph. Bascom AVR is popular in places like Iran - which has a search volume index of 100 for Bascom AVR and 0 for Arduino IDE, and BASCOM AVR has a search volume index of 1 in the US. Whereas Arduino IDE has a search volume index of 60 in the United States and 0 in Iran.
I would say that the Google Trends would indicate that Bascom AVR is the clear winner over Arduino IDE if your goal is to be with the "cool kids" in Iran.
More to the point, comparing a FREE IDE with a COMMERCIAL IDE is pure folly.
Let's compare the two in some real world applications that Arduino is being used in today. Let's see your Bascom AVR code to control a UAV. Let's see your Bascom AVR code to control all the timers and relays for a hydroponic system or a salt water aquarium. Let's see your Bascom AVR code to control a 888 LED cube.
I'll be waiting for ANYONE to show me that Bascom AVR can do that in less space.