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
You can compute for your ROI for Mining it or just buying it. Determine the time frame of your investment then compute the token that you will mine during that period of time and compared it when you just buy it and wait. The problem on mining was there is no guarantee that your rig will run smoothly all the time and also the coin you are mining might decrease value too over time. But since you have the advantage of free electricity, Mining might be profitable in your case, Just invest properly on your rig and maintenance.