Which gain option is best?

 
"Sliders at 0" is an old practice based on concerns about noise floor and the "taper" of the potentiometer/slider on analog boards.
 
Now a days it is just a convention that offers a convenience of familiarity.
 
If it is truly just a solo guitar... you can get there any way you want. Of course you may have some specific concerns about how hot a Vintage modeled EQ is getting hit or maybe a reverb send... stuff like that.
 
I'd probably put a maximizing limiter on the master bus and turn it up there.
 
best regards,
mike

I used to think I knew... but I realize that I don't think there is any way to discern what is appropriate anymore.
 
:-)

i would try an expander prior to any compression in the chain. since it's a solo, there's no other track to "cover" the noise floor. an expander can help get a higher signal to noise ratio so that when you do use the limiter, you don't "crush" the signal back into the noise as much.

Yes. I referred to that issue in the part of the sentence that looked like ""taper"".
 
I don't regard the taper of a potentiometer as an issue with a DAW... and frankly I rarely found it an issue with a good analog board either.
 
It always seemed like if you set the trim or input so that you had good signal level and some head room at the input that you end up with the fader somewhere that works out ok. Watching people slavishly turn down the input trim on something they want to sound quiet in the mix just so they can leave the fader at "0" seemed corny back then and I figure I still have that same opinion.
 
We used to have a response to folks who asked why the faders weren't all lined up at "0" (usually a well meaning guy from the band): "Why do you think they put the faders on this thing?"
 
I'm fairly comfortable with my personal opinion that it was and is a convention that more or less melts away when you start mixing and realize that the circumstance as a whole will lead you to getting the sound through ok or you'll figure out why it's not and and then it will get through ok.
 
 
Happy mixing!!!
 
best regards,
mike

Yes,  ignore the need to have it loud in the tracking stages. You have a volume control to get it louder if you need too.
 
I look to get a good solid input level. As Bitflipper pointed out, if the level is too low, as you increase it later you also increase the surrounding noise..... room noise, which you don't want. So work on getting a solid tracking level to start with.
 
I like to have my mics in fairly close to the acoustic guitar. Generally 12" or so. This ensures that I'm hearing the guitar as the predominate source and later, I can turn it up as needed without the room noise intruding and ruining the take.
 
In a  finger picking session, I'm sure the finger noises are part of the performance so close miking will get that as well. I know that when I record mandolin, I have the mic even closer.... sometimes 6" or less from the sound hole, and that grabs the pick sound on the strings which I feel gives some percussive character to the mandolin sound in the mix.
 
Shoot for a clean, well recorded session and don't worry in the tracking stages about the eventual final mix volume. There are plenty of ways to get the final levels up.....first things first.