I considered both and we ended up getting the suro.
The suro 20 has the humidity pump included with the incubator, the brinsea humidity pump is sold seperately so the brinsea with all the things the suro has would cost a lot more.
The brinsea pump has a built in resevoir, the suro has a tube you put into the water container of your choice (so really you could use a bigger container if needed)
King Suro 20. I liked it so much I sold my cabinet bator. In fact, my second King Suro just arrived today so now I'm selling my cabinet hatcher. The King Suro keeps the temp & humidity so stable I'm comfortable leaving home for the weekend. The hatch rate in both chickens and ducks has been outstanding. As the chicks fluff out I was able to pull them out even with other eggs still hatching because the humidity and temp recovers in minutes. Cleaning is a piece of cake. It's on sale right now at http://www.jmtdistributors.com/ JMT had the lower shipping cost.
3)The plastic bars for separating eggs are too flexible. The Brinsea has rigid metal bars.
4)In general the plastic feels thicker and more substantial in the Brinsea.
All but items 2 and possibly 4 are nitpicking. Both units are marginal as hatchers if they are fully loaded and the eggs all develop. Gets real crowded with more than 15 chicks.
I used the Brinsea Octagon 20 Advance with my class of 2nd graders last year.. we had 20 eggs and 10 chicks.. This was my first time doing this and I thought it was VERY easy and worked really well. We are putting more eggs in on Monday. I do not have the humidity pump but the humidity seemed to stay right where it needed to, as long as I added water to the bottom...
Good luck!
I can't comment on the King Suro, but I got a Brinsea Eco 20 last year, and I love it. I've had very successful hatches with the Brinsea (the first hatch was 100% with shipped eggs). It keeps very steady temps, is easy to regulate humidity, and very easy to clean. I got the auto-turn cradle also. I have 24 Welsummer eggs in my Brinsea right now--due to hatch April 9th.
Brinsea advance digital (with humidity pump) and suro 20 are apple to apple. Just big price difference.
Both bators are very good and not cheap ones.
I love my suro 20, it has all the function for a bargain price (compared to brinsea), I don't have to check temp. or humidity every couple hours.
I just ordered a brinsea eco 20 with auto turner, I think it will be the same with suro except humidity pump.