Well, we know the heavy rigid panels work well, and are durable. Some folks have had good luck with the light flexible panels. Some folks not.
Assuming weight is worth the risk to you, then the biggest flexible panel(s) you can mount would be good.
Do you have the yakima tracks on the roof? Are you doing the work? Are you willing to make some kind of support for the flexible panels so they have a bit of space under them for ventilation? Or do you just want to stick on the flexible panels and take the chance they won't work well?
And about controllers...
If you have room for two 120W+ panels (12V) or one big 240W+ panel (24V) then I would recommend the Victron MPPT 75/30 controller to go with these, along with the monitoring gear. If just using one 12V panel, the Trimetric 2030 controller and monitor are excellent.
Oh, and where are you buying this stuff? Canada? USA?