In general powerline and a second router...running as a AP will be better. If you have coax cables in both room MoCA is a much better option.
Mesh is very hit and miss with no way to predict if it works good in most houses. It take careful placement so it can get good signal from the main router and still send the signal to the remote room. This is very tricky when you have wall and ceilings in the path. Mesh/repeater you pay a large performance penalty in exchange for coverage. You really want mesh systems that have extra radios for the back haul connection. This makes the units more expensive but it helps with the performance.
Powerline might be slower than a mesh system. You might get 130mbps or so on depending on the wiring in the house. That should be good enough for most things. The key benifit of powerline over wifi is the latency is consistent on powerline. Wifi does error correction and when it gets interference you can get latency spikes. This only really matters for online game most other application can tolerate these spikes.