Pillow sizing standards

Looking to order Euro sham inserts online and I am faced with a dilemma...the sizes range from 22x22 to 26x26. Is there not a 'standard' size for Euro shams? If I buy the inserts and don't make my own covers I'm going to be stuck if I pick the wrong size!
Regardless, tho, what size do you think would LOOK the best?
The redecorating is heating up around here!

There are 4 basic pillow sizes from pillow guide:
Standard Pillow, 20" x 26". Put one standard pillow on a Twin bed, two across a Full or Queen bed, and three across a King bed. Uses a standard pillowcase.
Queen Pillow, 20" x 30". Perfectly paired across the top of a Full or Queen bed. Uses a standard pillowcase.
King Pillow, 20" x 36". Extra long and ideal in pairs across the top of King beds. Uses a King pillowcase.
Euro Pillow, 26" x 26". This large, square pillow is a great backdrop for a bedding ensemble and a good cushion for sitting up in bed. Uses a Euro sham.

I vote bigger is better.

Euros are usually stardard at 26x26.

Thanks! I'll go with the 26x26. Gotta head out to the fabric store in a week or so.