I want to know which one is a better choice. I know that 3k is from 2004 and 8k from 2001 or even old, but 3k hasn't a sampler like 8k. And I think that 8k has a better sequencer. And I know that 3k has a double price (1400 $).

Hi!
Most of us here don't own arrangers.
You may want to post your question at either "General Arranger" or "The Bar" sections.
You will get a lot more replies that way.

-ED-

I don't own arrangers but I want to buy one of this two. So, what can I do ? I own Yamaha W7 and Roland JV-1080.

Well,
As much as I want to help, I don't know much about PSR keyboards.
Do try http://www.synthzone.com/cgi-bin/forumdisplay.cgi?action=topics&number=37&SUBMIT=Go

Those guys really know their stuf. Mind you some of them hang out here as well. I just think that if you post right at the General Arranger section you'll get a lot more replies.

-ED-

Yes, 3351, you're right. I posted to General Arranger and I got some replies.