My 2 cents ....
A major controller manufacturer rates their 60-Amp unit at up to 800 watts of nominal panel capacity (for 12-Volt battery systems). Maximum panel power ratings obviously go up considerably at higher battery voltages, but that doesnít apply here.
The same manufacturer rates their 45-Amp controller for up to 600-watts of panel capacity (for 12-Volt battery system). That should also work but itís cutting it close, so Iíd personally stay with 60-Amp size.
With 6 panels, there are only so many ways to connect them, and most can be ruled out quickly:
One string of six panels in series I would rule out because voltage is too high, and itís also too susceptible to shade.
Connecting all six panels in parallel is best for shade, but current is highest from roof down to controller, so Iíd skip that option also.
Of the two remaining options, Iíd personally go with 3 strings of 2 panels in series each. The current is a little higher than 2 strings of 3 panels in series each, but the maximum voltage is lower, making it a bit safer. The system would also be a little less susceptible to spot shade.