It all comes down to what your final plans are for your rig.
If you're planning on building a full overlander, e.g. steel bumpers, sliders, winch, roof top tent, rear drawers, etc, etc, etc. then go with the heaviest rated springs.
If you're planning keeping it relatively stock with just suspension and tire upgrades, stay with lighter springs.
In your next post, give an idea of where you'd like your rig to be and I'm sure you'll get a lot of input from the good folks here that have built their rigs in so many configurations.
Also, you can go to the Builds thread here:
150-Series Toyotas
and find something that's built to what you like and see what they used or ask them.
Hope this helps!