I started a long thread about this on Facebook, most people believe the OEM is the best, but I don't like the open holes, it's not waterproof and the foot wells will fill with rain water and ruin my turf. I basically came down to 3 options.
1) The Poppy one listed above - I was told by someone inside in the industry that these are made by the same company with same material and pattern as OEM, but have a couple of improvements, like the waterproof venting in the rear rather than the gaping holes in the top front, and does not have the horrible white soft material around the handlebar area inside that shreds while trying to pull it around the bars.
2) I ended up going for this one from Covercraft. The material has very good reviews, and Covercraft overall good reviews in the realm of car covers. I like that it does not stretch around the handlebars, and it's solid, waterproof but breathable. $155 via ebay, there is a good picture there of it fitted to the ski, nice tight fit, but straight and not contoured around the handlebars. They are made per order, so the shipping time is long, about 6 weeks.
3) I have Seal Skin top of the line cover for two other skis, they are good heavy quality material and long lasting, but not a very tailored fit at all. Cheapest option of the 3 at around $110 with coupon code and free shipping.
I will spray a coat of Never Wet on the outside of the cover to repel water, it works great and I've done this in the past, just re-apply every few months. It's available at Home Depot. This combination should keep the ski dry from rain, but still allows the cover to breathe.