The yota motors are definetly good power plants, but I don't think that you could call them better. The 3RZ has definetly proved itself a good choice. Price, power and fit are all good. The 3.4 is a good motor, but much more expensive. The inline 6's create more fabing and moding but have good power. The 4.3 fits nicely can be had fairly inexpensive compared to most of the others and there is definetly a large aftermarket.
I think you have to weigh all the factors for your particular situation, ie. the type of wheelin, kind of power you need, cost, fabing expertise vs. bolt on etc. Then find the engine that best suits your needs.
I was always a toyota or nothing kind of guy, but when I built my runner, for the power, ease of install and overall cost the 4.3 was the best choice for me.