Hi Dave, although I have not heard a guitar VSTi that sound real, check my avatar to see why, but I did a google search for “guitar VSTi” and there are quite a few free ones here.

I have read that there are a number of good sounding ones for Kontakt such as these and these
However they can be on the more expensive side.

A less expensive one here
has received good reviews.

Also Kontakt comes with some guitar sounds. Have you tried them?

Since I do not know how you will be using these guitar sounds I can not help you with that. However I will say that if you expect to take a BiaB generated midi file, drop it into FL Studio, pick a new VSTi and think it will sound more like a real guitar you are in for a big disappointment. You will need to greatly modify any Midi guitar file to even come close. You will need to use the pitch bend (vibrato, slurs, pre-bends and bend, slides, detuning, etc.), the mod wheel (tremolo, etc), configurable fader and/or knobs (hammer ons, pull offs, legato playing etc). It will take a lot of editing to achieve that almost real sound and I haven’t even gotten into cabinet choices and effects as they also are needed.

I don’t know what you are using for midi input but if you don’t have a midi controller keyboard with assignable knobs and faders you will have to input/draw the data in the piano roll view.. I use one like this model .

I hope this helps.

Whenever I get something stuck in the back of my throat, I dislodge it by drinking a beer.
It's called the Heineken Maneuver.

64 bit Win 10 Pro, the latest BiaB/RB, Roland Octa-Capture audio interface, a ton of software/hardware