Disregarding any additional upgrades you might want to dish out on then, at 25 points which is better as written? Turr phenir or royal guard with PTL?

Both have advantages; RG has the worse pilot skill, but more choice in his second action and is more likely to be able to get his second action (needing only to not have a stress token, where as Turr needs a target too). Obviously the big difference is that Turr gets his second action without incurring a stress.

I can't decide for the life of me which of these is actually better. Anyone help?

Probably the flexibility of the Royal Guard.

It can turtle up (focus & evade) for defense or arc dodge (barrel roll & boost), or any combination of, really.

But being able to do both it's actions early in the round means it will be able to get into (or out of) firing arcs much more effectively than a nekkid Turr can.

Both are fine choices, but as a redhead, I like to represent the RGP wherever possible. Fealty to the Empire!

RGP w/ PTL is more flexible than a naked Turr.

Honestly, I would probably rather have Lorrir than a naked Turr and save myself two points.