There is most famous index on a "Coinmarketcap" -" BTC Dominance". Because of the two different main types of blockchain projects : "platforms" and "comsumer-oriented"; think it will be good to have different types of indexese. One of them dedicate to the comparing of 'platform-blochain projects'.
According my crypto-market expeirence will chooce the next blockchain projects : Bitcoin, Etherium, Bitshares, QTUM , EOS.
The formula of the Index = (Bitshares + QTUM + EOS ) / ( Etherium + Bitcoin )
Etherium will be added to the POW part of index. When Etherium will migrate to the Pos-consensues the historical meanings of the NoPOW/POW Index will be recalcuted.
On the 30.06.18 10.00 UTC the first meaning of the index is equal - 5.366%.