Batteries - What do you use

I have four Trojan T-105 6 volt batteries. This is the second set I have used. The first set lasted 12 years and I used them on two different trailers. They are great, but I service them about four times a year. Usually all it takes is to make sure the fluid level is full. I have room for two more, but I don't think I'll ever need them. I keep them charged with a 144 watt solar panel. Works great, but you can depend on the solar not being very effective in winter as they are flat on the roof and the sun angle is low. A portable solar unit would be more effective then.