I too would choose AGM over Gel, but mostly because the selection and price competition is better. Functionally they are similar. We've been using AGMs in our coach for the past 11 years with good results.
However, the most cost effective house battery is the GC2 golf cart 6v deep cycle. Probably half the price of AGM or Gel and the same perfromance & longevity. The only draw back is that you have to occasionally check the water in the cells and add if needed. With atop quality charger that's probably a 1-2x per year chore, but with a less capable charger it might be every 1-2 months. The AGMs and Gels are sealed and do not require checks. They also don't vent gases that can corrode the metal in the battery tray & cables. A nice advantage, but costly.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL