Trace and Xantrex are the two brands I find most in the RV's I work on. If you get the inverter/charger models, they will do the battery charging for you when connected to 120VAC, provide 12VDC and have an internal auto transfer switch for when 120VAC is present.
Thay aren't cheap, but are well worth it if that's the direction you would like to take.
BTW, They are both made by Xantrax now!!
Lew Farber...RVIA Certified Master Tech...ABYC Certified Master Marine Electrician
SOLAR TECH ENERGY SYSTEMS, INC.
AM SOLAR ...MAGNUM…VICTRON ENERGY...LITHIUM & LIFELINE BATTERIES…MARINE REFRIGERATION