Something to consider about the Myrmidon is that, in addition to being the first fighter you gain access to in FS2, it's also the only one available for quite a long while with more than four gunpoints. If you're looking for a fighter with loads of primary firepower, before the Erinyes becomes available, it's either the Myrmidon or the Herc I (which has lousy placement of its gunpoints). It doesn't make the fighter any better, but it does explain why you might give it a fair bit of flight time, despite its weaknesses.
Personally, I'm partial to the Thoth and the Seth. The thin profiles of the Vasudan fighters is a great boon in a dogfight, and with the Thoth in particular, there's nothing quite like fitting a Mekhu-HL7 and painting the night sky red. I'm not sure why I prefer the Seth to the Tauret, to be honest, but on assault missions, I always find myself choosing the older of the two.
On the Terran side, you can add my name to the list of Perseus pilots. It's just a good mix of speed and durability.
Among bombers, I tend to favor the Medusa. Again, I'm not sure why I tend to favor it over the Artemis, since the turret isn't a huge advantage, and each secondary bank carrying an odd number of bombs is more an irritant than anything else, but given the choice, I take the Medusa.