Reliable and durable for offroad lithium battery recommendation needed for DIY trailer

[GEONat]

In about 3-4 weeks I should be ready to slap in a couple batteries into my DIY offroad trailer. I've not even stated down the battery side of things or power management, but seeing that I'm asking questions, might as well roll out another here! Let me know which battery you are using in your trailer. Look for lithium (I think). Thanks!