Here are my 2 cents.

I'm a MAX and C4D user and I have some exerpience with XSI and Maya.  The basic advice of trying all the demo's is still the best thing to do.  One thing you can do is a google serach for a comaprision chart of the major 3D apps.  They all have their pluses and minuses.

For example (in my opinion) MAX is the hands down best at tweaking a poly.  It has more tools and more things you can do with it than any other application I have tried.  Max also has a massive amount of plugins you can by and lots scripts from places like ScriptSpot.  Starting with version 8 Mental Ray was included as part of the Max package.  The scan line render in Max is quite powerful but you really have to understand lighting to make really good use of it.   The animation tools in Max (Character Studio) are very powerful too, but they take alot of work  get a good grasp of.  Now Max has a steep learning curve there tools panels intimidate many users.

C4D I like it for it's interface and easy of use (at least for me).  The tools are easy to use and it's default render engine is quite good and rather fast.  It's poly tools are limited when comapred to MAX as well as it's animation tools.  I like the texture editor in C4D more than the one in Max, you get lost in the one in max real easy.

Lightwave - for me I could never get a good workflow and I havenn't used it since version 6.  I'll let someone else fill this in.

Maya - A pretty GUI to hide all of the MEL script ( that is basically what it is).  Modeling tools I found to be fair.  The animation tools are quite good, easy to use than Max (at least I think so).  The render engine is pretty good, but there are external renders that are better.

For landscapes - I'd use Vue over Bryce.  I find Bryce clunky in comparision.  It's mainly work flow issues for me.  I also think the render engine in Vue is better.  The other plus with Vue is xStream.  This lets me use my Vue objects directly in Max and C4D.  It's a really nice feature if you want to pay the cash.

Rendering.  Well your assumption is not correct.  The more powerful the render engine, the more powerful the features, and the more realistic render it can make - the LONGER it takes.  The ONLY thing you can do is add more CPU power and more RAM at it.   As an example my render system is a Dual AMD Opteron with 8 gigabytes of RAM.  This is just for rendering nothing else.  The only way you can do better is with a big Network Render system.

Also launching a render before you go to bed or before you go out to dinner is another way to get it done.  Like I said the better the Render Engine the longer it can take.

Best of luck and if you have any more questions please ask.