Routes South from Bogota

[RickMcD]

I will be flying my KLR to Bogota (from Panama City) in late October/November and heading south for TDF. Looking at my Colombia map there seems to be two ways to head south toward Ecuador. Hwy 45 past Neiva then east to Popayan OR a couple of other ways east (south first) to Ibague, Armenia, Cali, etc. or northeast to Manizales, Tula, etc. What route do most use? Which do you all recommend and why? Thanks for the input.