What size wire should be run from the power company's transformer to the meter for a 200 amp service. The distance from the transformer to the meter is about 150 ft. Can direct burial cable be used or does conduit need to be used?

4/0AL is typical for this.

Direct burial is fine if soil conditions allow it.
I always use conduit.

Some utilities require the customer to furnish and install the underground feeder from the transformer to meter.

You should consult with your utility, as most can tell you what the size should be for the amp rating and distance.

This is the page from my local utility, that lists a 200 amp using #4/0 Aluminum can be up to 220 feet.

#4/0 would be the minimum size for 200 Amp.

Thanks for the info!