For me, wear is one of the biggest deciding factors. Strike for me comes next, especially when we are talking about uncirculated coins. But for coins that are not MS, I take how much wear is on the high points of the coin.
I voted tone since I collect rainbow toned coins exclusively. However, I think all of the factors play a role. Certain compositions don't tone significantly and circulated coins are rarely rainbow toned. Luster is very important since it greatly affects the overall appearance of the toning. Strike would be the least important factor IMO.
I voted other because for me the #1 thing I look for is eye appeal. I won't buy a coin if I think its ugly. However, wear is a very close second for me.