My trailer came with the typical cheapy
Bargman 92 series tail lights. I was never happy with the pitiful light they put out, so I replaced them with the
Bargman LED 84/85 series.
The new lights' brake light function is VERY bright, which is what I wanted. Comes in handy when backing into a site at night, as I only have to tap the brakes to light up the area behind the trailer. They are also large enough to cover all the holes from my old tail lights.
The only downside was I had to mount a separate tag light/holder, but it wasn't a big deal.
Edit: I should have added, no resistors required for my application on the trailer. I also would not recommend installing the LED 'bulbs' in housings designed for incandescent bulbs, as the light pattern will not spread/reflect properly. I've seen folks in my area install those in their cars, and it turns their tail lights into a little dot of light behind the big lens.