Portfolio piece choices

Busterizer

I need to get my portfolio to much better state than it is now. And since I don't know (can't decide) in what to specialize in, I was thinking of doing a few a few props, weapons, and character just so I cover all the bases.

For prop I was was thinking of doing something insanely complex with many pieces and details but not sure what exactly. Same goes for weapons and characters, I have a few things in mind but I am not really sure what is really interesting to look at in a portfolio (I don't wish to do 'yet another AK-47').

My question is what do you guys regard as interesting portfolio piece?

Tobbo

I personally wouldn't try to cover all the bases with your portfolio. You'll improve much more quickly if you're not trying to get really good at everything, but can narrow your focus down to something specific. Odds are with the 'cover all bases' strategy you'll end up being mediocre at everything and good at nothing. 

If you're considering characters, you're going to have to study quite a bit of anatomy. There's no way around it.

With portfolio pieces, it's true that you don't want to do something very basic, but at the same time there's no point in trying to do the most complex thing you can find. You want it to be interesting and still be able to execute it really well.

Just do a Google search for 3d environment artist portfolio, 3d prop artist portfolio, 3d character artist portfolio, etc. 

You should be able to get a pretty good idea of where the bar is. 

Kel-Shaded

Complexity makes a piece time consuming but not necessarily interesting, 
Mini projects are a good idea, things you can pump out in an evening or a weekend, The more of those you do the closer you'll get to finding what you want to specialise in, learn stuff on the way, and have a body of work you can split down the line as bland generic or weird creative

RaptorCWS

well this is not too much more complex than an AK, but this is a WWI gun and I have not seen too many people with it in their portfolio.
https://en.wikipedia.org/wiki/Lewis_gun