There are two main line bucket trucks, Altec and Hi-Ranger. These are the two seen most often in use by line companies and Utilities.
Both have their charms, I've had 2 friends nearly killed (and known several who were killed) by leveling cable failures in the Hi-Rangers. I'm sure they will say "If you have it inspected adequately, it will be no problem" It may be true, who knows.
The Altec is very well built and engineered, the biggest difference is speed. The Hi-Ranger will actually leave you standing in mid air it's so danged fast - NOT necessarily a good thing, especially for an occasional bucket user.
If I were to buy only one, it would be an Altec line truck. It has an auxiliary bucket on it, but a very useful boom. It is slow, but again, if you are only occasionally using a bucket, that really doesn't matter, and the 5 ton boom comes in real handy.
Just my .02
