I would suggest Bryce for both the ease and cost, version 5.5 is still free thru DAZ. Blender is a great open source (free) app with a strong user base but to be honest has a steep learning curve. If you enjoy 3D Modeling and have the time it is worth it to explore Blender. It has grown in capability at a phenomenal rate and has some exciting features including a new UI coming later this year.
David

Here are links to a couple simple Bryce renders I did a while back:

Bryce 5 in 2005 http://i.pbase.com/o4/47/589247/1/48139197.JesusFishOrnament.jpg
Bryce 5.5 in 2006 http://k41.pbase.com/o5/47/589247/1/68084456.QRtSB6f4.TorusKnotatSea.jpg

Here is a basic Blender image I did recently via a MoI lamp base tutorial. It was done as a test before purchasing MoI: