Having experienced both, I think Virgin are great and FGW are dreadful.
Designing a market for train services is tricky. Leaving each rail operator permanently in charge might lead to stagnation. Reshuffling franchises every few years puts civil servants in charge of the market, and can make the operators short-termist. My instinct is to prefer natural monopolies to artificial competition (have I mentioned the Russian chandelier factory?) but that is just from the gut.
I travelled across Germany on Friday. Every train I used was late, I was delayed by 2 hours in total, and there was a replacement bus service on the last part of the line.