I have both crown and v8 so I figured I'd weigh in here.
On the Arctic question, the V8 is only compatible with coils designed for the V8, previous version arctic coils will not work. That being said there is a slew of coils available ranging from the V1/V2's to the V4's V8's, and the new tiger, hive, and snake coils. All of these coils will work with the V8 and V8 mini tank.
It is a fantastic tank with great flavor, good build quality overall very easy to use, clean etc. I did have some paint chipping with my black one on the inside lower section where it meets the glass, but nothing alarming. No issues with my stainless or gold one full size and no issues at all with black or stainless mini. I have not had any wicking issues whatsoever across all ranges of liquids. Coil life has been great, lasting 3-4 weeks, followed by another 1-2 after boiling.
I like my crowns (have many of them), the coils can be hit or miss and take a good bit to break in properly, however after taking the time to do they reward you with great flavor and nice clouds. Have had some issues with dry hits with a few of my crown coils when pushing higher wattages, but no issues keeping the .25's around 65-75 watts. Many on here take their's much higher with no issues.
On TC question, both will work well however you will have more options with the crown as the only ss / nickel coils for the arctic are the v1/2 as opposed to the crown with the .15ni, and .25/.5ss. Although I am not sure if the arctic v8 claptons can be used in tc? Someone wiser on here I'm sure can answer that.
Cloud wise, I would have to give the edge to the V8, with either the V4 or V8 coils my room is constantly clouded and at risk of setting of every fire alarm. The crown does put out incredible vapor, just not as thick and dense in my opinion...now my new rafale...that's another story!