Considering fees and profits, but also the best thing for the Monero network, which is the most valuable solution?
Also, is it depending on hardware and hashrate power?
Thanks in advance.
It's for sure the best thing to join a pool - unless you have a really high hash-power. If you own a data center you can go on and solo mine but in nearly any other case, it's more profitable to use a mining pool.
Apart from profitability, for the Monero network it doesn't make a big difference if you solo-mine or not.
In general, you of course need "good" hardware to get a high hash-rate. A really fast CPU or GPU is what you need. Everything else isn't significantly important. GPU mining is more profitable than CPU mining.