Top 5 Options

I read the OP's request as asking about options one might consider adding to a trailer, not features to look for when selecting a trailer ...

"However, one of the things I'm trying to figure out is what are the top 5 options I should make sure to have (like wired for solar, dual batteries, etc.)"

Sorry, TMI, but here goes. My number one concern was a bathroom size and layout I could actually use. I'm a big guy and it had to be big enough for me to be able to sit without having my knees forced together and sit with my arms crossed. I wanted to be able to reach to wipe my butt, not scrunch my face into a wall when I bent over to wipe or contorting myself and falling face first into the floor when trying to wipe. My older trailer required me to step one foot into the tub when wiping. Some trailer I looked at I would look at some of the amenities and features, but every trailer I entered I would go straight to the toilet, close the door and sit on the throne. Many I walked straight out of and on to the next one after only checking out the bathroom.

The second was a big enough shower to stand upright in and not feel like the walls were going to close in on me and I could actually bend my knees to reach and wash my feet.

Third was waste and FW tank sizes.

Fourth it had to sleep 4 without using the dinette.

Fifth was cabinet storage space.

Power tongue jack, fireplace, big fridge, 2nd air conditioner, vent covers

Without knowing what you are considering, it's impossible to help you. For us, it's adequate counter space, an oven, storage in every possible spot, a toilet you can sit on and use to wipe your butt, and good insulation (double pane windows)

Raider Battalion wrote:
Maybe I should ask it slightly differently. What are the top 5 options you have found most useful?

1) EMS w/Surge Protection

2) BAL Standard Tire Locking Chocks to secure the trailer, BAL X-Chocks to minimize camper wiggle, custom Lynx / Wood leveling system

3) FloJet Waste Macerator Waste Pump so I can service the tanks at home and never have to line up at a campground dump station, eliminates the need to drag a wheeled tote tank to the dump station

4) Fresh Water Pump quieting, so quiet it barely can be heard

5) Fresh Water Transfer System

Pics with text description are in my gallery. :)

Maybe I should ask it slightly differently. What are the top 5 options you have found most useful?

If you ever plan to camp with shore power then an EMS w/surge protection is HIGHLY recommended to protect your trailer's electrical system from the many errors not uncommon with campground power.

That depends on your life style. If you will never boondock, then you don't need dual batteries or solar, to use your examples. True for all options.