Sumo is pretty undervalued right now, i like that coin, the developers are doing a great job on it.
I think 2018 will be the year of privacy coins. It is hard to tell which one will gain the most, my bet is the ones with low market cap like ONION, BGX, SUMO, XSPEC
And onion is not a good coin, of course not, we do not even know who are the real developers of it (or if they really exist)