1. Bitcoin
2. Ethereum
3. Monero coin
4. Ripple
This is probably the best approach throughout the thread. Bitcoin is king of crypto 1.0, Ethereum is that of 2.0, and Monero is king of dark web. Like it or not (and I personally do not) Ripple is good because it has its massive warchest and a solidified network of clients and partners in the financial sector. It seems to be equipped to set out what it wants to do.
Alternatively, that 4th slot could to go your pick as the winner of blockchain 3.0. Current contenders are ADA/EOS/NEO/QTUM/NEM/etc... I personally have the most faith in NEM, but it's a preference call at that point.