The question is not that difficult...
A. If it has to be Canon and they can't be the same, I'd start with:
1. EF 1200mm f/5.6 L USM
2. EF 600mm f/4L IS II USM
3. EF 800mm f/5.6L IS USM
B. If it doesn't have to be Canon and they can't be the same, I'd start with:
1. Leica APO-TELYT-R 1:5.6 1600mm
2. Zeiss Apo Sonnar T* 1700 mm F4
3. EF 1200mm f/5.6 L USM
Having sold all three and depending upon the set A or B, I'd buy better or worse house or palace, boat and a car with alive driver who'd bring me from his first test drive to downtown three decent lenses: 24 II, 85 1.2, 70-200 II...