I would go with a concrete tank. The plastic based tanks all seem durable, but locally when pumping out any plastic or fiberglass tank they tell us that we have to refill the tank with water to protect against possible collapse. With a concrete tank, you pump it out, cover it up and forget it, and the drainfield lines get a much needed rest for a few days so the ground can semi dry out as the empty tank refills. With a plastic or fiberglass tank you have the added cost of hauling in anywhere from 750 to 1500 gallons of water when you empty the tank, and since you refill the tank with water the absorption system never gets a rest. Concrete costs a little more but if you buy one that is reinforced (rebar or steel mesh) it should outlive you and probably your children as well. Speak with Mike50 about this as he is going through a replacement now.
If you are going to be there for a long time-get concrete if it's in your budget as it will last as long as your home does.
My concrete tank goes in next week. If I had planned on only being here for 5-10 more years then I would Not have spent the extra money and opted for a synthetic which is much cheaper.
Fiberglass tanks, which is the option to concrete here, can collapse from the weight of the ground above them, and it can happen whether they are filled with water or not.