Neither of those even with millions of users (and especially if you expect them to be on mobile) will be sufficient to secure the chain against powerful attackers such as botnets with gaming rigs and hijacked Amazon EC2 or other VPS cloud accounts.

I also suggest these two References from my (yet unpublished) white paper:

⁴⁵	Paul Sztorc. One Chain to Rule Them All.  Truthcoin.info blog, §Only Bitcoin’s Hashrate Stands a Chance, Mar 7, 2016.
⁴⁶	Mircea Popescu. The woes of Altcoin, or why there is no such thing as “cryptocurrencies”. Trilema.com blog, Aug 16, 2014.

Also (even unprofitable) mining on CPUs enables 51% rented hashrate attacks! Kiss Monero's (and Zcash's) ass goodbye if they don't get an ASIC implementation. Komodo might possibly be a better bet because @jl777 adopted my suggestion to use Bitcoin's blockchain for security.