I've owned a couple of pioneers and I'm currently using an alpine. I'd happily recommend either, depends how much you wanna spend?
I think some of the pioneers have bluetoth built in, whereas the alpines dont, youll need to buy the adaptor. You do get more pre-outs for the same money with the alpines tho.
It depends on what you wanna do, you gonna be running subs and components?
Both of these are about as good as most people need:
http://www.caraudiodirect.co.uk/alpi...ri-p-6423.html
http://www.caraudiodirect.co.uk/pion...ub-p-7225.html
You'll need to buy a lead to your ipod whichever one you buy.