Both. Today I got a 1916, a 1918-S, a 1923, 1935, 1939, 1940 and 11 other wheats from $40 worth. Nickels were so so, but not usually - I usually find a buffer or a war baby.
I would always do nickels. I have actually never done a box of pennies but I don't think I have the patience for it; plus, I'm not into all the different varieties and I would hate to dump the copper knowing that it's over 2 cents per penny. However, I'm not a copper hoarder so I stay away. On the other hand, nickels are great because you can find low circulation Jeffs, War Nickels, proofs, key and semi-key dates, Buffalo, V-Nickels and, my dream, would be to find a Shield Nickel (still haven't yet).
Oh, I searched a lot of nickels last week - found several silver babies - but the best by far was the '45-P with about a 15% clip at 12 - 2 o'clock. I love finding really old errors. The second best is the 1960 Irish tanner. Never ever found a predecimal Irish coin in a roll search before - only euro things.
I did a box of pennies once... it took me 6 hours and only got like 6 wheats yet when i go to the bank and get like 5 dollars worth of pennies il get like 15 wheats. There are only 4 years for silver nickels (or it might be 3) so im getting 500 in halves and 500 in dimes which have the highest percentage of finding silver, but still a fraction of a percent
