I think that both are pretty undervalued at the moment, so you are probably better off diversifying your investment 50/50 among the two coins. Lisk has some pretty awesome community and so has waves, and in the end that is what going to drive the price up eventually.

As i said - diversify instead of seeking one coin that you want to invest all your money in. And holding some waves and some lisk makes a lot of sense.

$700 is not a lot, so consider trading short term and hold long term instead of holding all the time.