Hello From Razorbackdave!
My favorite cache so far is (GCKQWY) "GF465 S5 Tunnel" The cache is at the entrance to an abandon hand dug train tunnel (1890's) about 10 miles NE of Eureka Springs in the mountains. This cache is a great adventure to find.
My next favorite cache so far was probably (GCKH8H) Arkansas's 1000th Cache: B-25 Crash Site. This cache is up on a mountain a little south and west of Jasper up on Round Top mountain. It was a great adventure finding this one also.
Both of these cache's took a little priliminary re-con to find the best way to find them. Happy Hunting!