Loja is a nice area in terms of nature and culture, but ugly women and boring, so not the preferred choice.
Cusco has ugly, but very easy women and is a vibrant city with nightlife options nearly every day, tons of tourists and many sites you can visit, even outside of Macchu Pichu. Not a bad option for a month I'd say. You can also try your luck with all the tourist ladies and food etc is quite cheap.
Chia I don't know about, but it will probably be the best place for hot women and given the proximity to Bogota there will be options for having fun, but it might be a bit small to have fun on regular days when you can't go to Bogota.
Cusco has ugly, but very easy women and is a vibrant city with nightlife options nearly every day, tons of tourists and many sites you can visit, even outside of Macchu Pichu. Not a bad option for a month I'd say. You can also try your luck with all the tourist ladies and food etc is quite cheap.
Chia I don't know about, but it will probably be the best place for hot women and given the proximity to Bogota there will be options for having fun, but it might be a bit small to have fun on regular days when you can't go to Bogota.