My preference is HP followed by Epson. I have an Epson R300 and bought it because it has a tray to print CD/DVD labels. Occassionally it has a problem requiring the cleaning of the print heads. It can be tempermental. Output quality is terrific.
On my Christmas list is the HP8750 ($500) which will do 13x19 paper - allowing for 12x12. I had a HP1120C (never had any serious problems with it - only real problem was/is west TX dust) that I bought many years ago and used it on my Win95 system. Two weeks ago it gave up the ghost. The Win95 system gave up the ghost as well. I've had it since it first came out and paid $500. I also have an HP 7450 that I use for some minor work.
I think the world of HP printers. My Epson gives me great results too but can be tempermental.
Printing 8x8: My guess is to print on 8.5x11 and trim the excess. My recommendation is to invest in a good rotary trimmer. Expensive but if you do a lot of work requiring trimming the rotary is the way to go.
Paper and ink: I only use the manufactures brand. Why take a chance on getting something that is not up to standard or that will damage the printer. I'd rather play it safe. I use only one brand of paper - KODAK ULTIMA (8.5x11). I found that the first print in my Epson and HP just came out perfect. And supposedly 100 year archiveability with the normal inks with the printer. I have not noticed any fading or color shifting under normal storage and viewing conditions.
If Santa Claus brings me the HP 8750 I'll spend $30 and get some of the Office Max 13x19 paper. But more than likely I'll get Kodak or one of the other pro papers that I found on
www.adorama.com.