I can't talk about STFs but I have been in mirror events where we were all in the Oddy, they were the fastest ones I have played in yet. I like that event so much I do it whenever it pops up at a reasonable time for me so I have a general idea on how long it takes. It was only 10 levels later I realised it gave dilithium so that was not an incentive for me it was them being enjoyable.
As others have said it is really down to your playstyle and what you enjoy. Every ship has its strength and weakness learn to work with them and not around them is how you become a better player, and yes I am still learning soo this is not from some uber player perspective just some average player perspective.