Bryce – easy to use, a bit buggy and slow to render.
Bryce can do some amazing stuff and as Horo said treat it like a game and explore. It is fun to use I must admit. Trying to compare Bryce to anything is like apples and oranges.
Cararra 8 Pro – not as easy to use as Bryce but still fairly straight forward, too buggy for me to use and will not be paying for an upgrade so for me Carrara is no longer an option unless I go back to 7 Pro or 6 Pro. But as a full package goes not too bad at all.
Vue - well I love Vue for many reasons. If making detailed landscapes etc is your bag then Vue is the way to go in my opinion. But you do need a powerful computer to get the best out of it.
But consider the price differences between them all. For its price Bryce is one hell of a program if you are prepared to learn it.
Vue was designed with Environments in mind and that is what it is good at. Bryce can do them but IMHO not as well compared to Vue. Carrara on the other hand is capable of giving some great results and with the added benefit of the modelling room which Vue and Bryce don’t have. Plus it has particles and physics.
So it all depends what you want, what you want out of it and how much money you want to spend. Are you prepared to work had to learn etc etc.