On a recent 2205 project (small vessels and small/medium piping) we some trouble with the GTAW root passes (ASTM A923), but GMAW turned out to be very reliable on medium diameter piping and vessels (horizontal-rotated position), in terms of ferrite/austenite balance and corrosion testing. We did not attempt FCAW but I would recommend synergic pulsed GMAW with 0.045 or 0.035" wire. If you want to avoid Far East sources, which can be mandatory in the USA, Sandvik is the only way to go.
UNS S32205 has become the de facto standard for 2205 base metal, and it means freedom from nitrogen-bearing shielding gases that were necessary with S31803.
My very broad experience is that the higher you go up the CRA ladder, the more cost incentive there is to use GMAW, while FCAW seems to grow more challenged technically (though more user-friendly).
Hope this helps.
"Everyone is entitled to their own opinions, but they are not entitled to their own facts."