Both. Some Bitcoin here, some Litecoin there. You won't be sorry if you had both.
This could be a really good idea but currently buying ltc for a double profit seems hard as other coins like waves , stratis are significantly increasing
Bitcoin is easier to convert into fiat than litecoin so if I will choose between the two, I will invest into bitcoin. Also, I think if potential growth is discussed, bitcoin got more of it than litecoin because there is not a lot going into litecoin lately, while there are many developments are happening into bitcoin. Even if that's the case, I would like to invest in both because both still got potential to grow.
Seriously that is the excuse you are going to give to not buy ltc because you can't easily convert it to fiat. Currently ltc is listed on most of the exchanges and there is always something like shapeshift so conversion to bitcoin is surely not a issue and some exchanges surely provide ltc/usd trading options