Which is the best strategy for the future
1. Buy altcoins and hold for the next halving season
2. Build mining rigs and start mining some coins like ravencoin and ergo to hold some for the future
Mind you I don't pay for electricity bill cos I have solar installed
Your idea is both good, it is good to mine altcoin but I will advise you to mine altcoin but after you do your profitability rate, if you are mining a coin now and you do not gain, do not mine the coin, mine only the coin you can gain from, it will be your choice to sell or hold. You can also buy ravencoin, but know that altcoins can be disappointing in bear market, the price can still low, but you can risk it.