I just moved back home in January and I would go with the Highlands. I say this because the Highlands is closer to the parks and there is more nightlife. The running in Louisville is awesome. I have lived all over the US and I think Cherokee and Seneca parks are two of the best parks in the country. And then you add in Iroquois and the surrounding parks and you have some great running. Check out the Triple crown races and the Kentucky Derby mini marathon. I don’t know much about the cycling and triathlon scene because I didn’t ride when I lived here before.
You can swim at the University of Louisville pool for $40 a month. There is also the Mary T. Meagher Aquatic Center that is $38 a month.
If you have any other questions let me know.