not so familiar w/ mental ray. I think only nerds use this?

I would say maxwell is not your choice for animation, as speed is an issue (although their new version may have addressed this to some degree). Very nice quality if you have the time to wait for it. And a moderate (to steep?) learning curve.

for non photorealistic-- you should just use something like podium--basic nice, diagrammatic quality--also achievable in other renderers w/ an ambient occlusion pass (or in vray, vray "dirt" material)

I would learn vray for 3ds max or rhino--

mental ray, but I am biased. I have invested the time in getting to know mr and bought the 3 book series by 3dats. I also kind of feel like since it comes with 3ds max you dont have to spend extra money on a render program. mr really does produce some of the best quality renders in my opinion. I'd be happy to take the conversation off board and share some of my work if you really are interested.

maxwell = great for quick render setups that don't require too much attention or initial setup time.

mental ray = most advanced renderer of them all. if you spend some time learning how to use it right, your render quality will be far far above of that which you can achieve with maxwell.

as for the question of diagrammatic renderings; you can do those with pretty much any program + photoshop/illustrator. buying something like podium or penguin to do those is pretty much a waste of time and money if you have maxwell or mental ray already and a basic knowledge of photoshop/illustrator.

Personally, I would recommend VRay over Maxwell. I find that VRay is just as quick to set up, but gives you a little more control over materials that Maxwell does not. Also, I feel like it renders faster. The pro of Maxwell is that it renders something really quick and then gradually refines it if you let it sit long enough, but I find it's hard to gauge what the final image is going to be in the first or second pass.

Mental Ray is of course a far more advanced engine and can produce some amazing results. The problem with MR is the learning curve. Don't expect to just plug in some materials and hit render. It's an investment, so if time is an issue, better to stick with VRay.

While I'm inclined to agree that VRay can be faster than Maxwell, Maxwell 2's material editor gives you 20X more control than the VRay for Rhino editor; add to that lens options and on the fly lighting, the control offered by Maxwell far surpasses what VRay for Rhino has to offer.

I'm forced to use mental ray for renderings as our corporate visualization team enforced it as a standard for all our renderings -- so no more vray.... :(

Maxwell is very nice but I haven't heard much about it lately....I would just stick with MAX as there is a better likelihood that firms will need that from you due to its popularity and history.

impressions from a beginner's perspective:

maxwell has a lot of nice plasticy looking materials. also, i think the sliders to control the lighting (and ability to make light emitting materials) is relatively intuitive as compared to mental ray. i also like the ability to tweak stuff after it's started. i've only used maxwell with rhino. truthfully, i generally just default to vray because it's sort of just the most intuitive (for me).

i would welcome suggestions for a good book/website/whatever for either rendering method (and VRay).