Your mistake is only asking what coins will support Lightning Network and not asking what coins have segwit and will get LN support because that is the thing. You need segwit enabled to profit from the features of LN at its fullest.
In this sense, LTC is the coin that is best positioned.
I'm highly invested in LTC and I can see LTC aiding BTC in overcoming their fee issue. People can transfer their BTC to LTC when they need to make quick transactions and not have to worry about paying some ridiculous fee. I always thought the LTC & BTC partnership was just marketing, but i'm starting to see some legitimacy.