Which 3d format would you suggest for loading models into a 3d engine which has good support for animated models (bone animation, etc)? 3ds is really old, .X doesnt seem to be the best option. Whats your opinion?

.x is well suitable, but a bit hard to parse - there's a lot of exporters available for all 3d modelling packages, but they differ largely in quality. Collada is reliable as well, and has high-quality exporters for 3DSMax and Maya, other packages do support it as well. But the format itsself is very complex, you'll have to invest a lot of work until you support all the features and options. The Doom3 .md5 format is nice as well, if you find exporter plugins for it. Maybe MS3D, but I'm not sure there.

I hope you don't me putting a quick commercial here: the Open Asset Import Library supports loading both of the formats mentioned above, and about 20 more. You don't need to write the file loaders for yourself.

I have seen collada...from what i've read it is quite good and is supported by most 3d vendors. I guess this should be the best choice in terms of features (not easiness of writing a parser for it).

What are the limitations of it?

I first started by using the Caligari trueSpace file format because it was easy to parse. After a while I transitioned over to FBX because it is supported by Maya and has a good following. Now what I do is I still use FBX to export my data, but then I run it through a program that I wrote to optimize the format for my game engine. Within my game engine I only use my own file format. I've created video tutorials showing my entire progress on my website. If you are interested in the FBX parser code, have a look here: http://www.marek-knows.com/phpBB2/viewtopic.php?t=353

After having a look at collada, i decided to go for something that looks more....er...stable. I have started parsing FBX files. Samples look good, skinned animation is supported well...so it looks fine so far.My purpose is to convert it to my own format later on. I will have a look at your website. Thanks man.