I too think cut sunfish is the best channel bait. I catch sunfish (I prefer green sunfish, they're hardier and live longer on the hook) for live flathead bait and some always die in the livewell (badly hooked). I recently started cutting these up for channel bait and have had better success with them than with any other bait. Frozen squid is my second choice.

Yep...fresh cutbait is hard to beat. I caught this 26lb. flathead on cut 'gill while fishin' for channels. I have since targeted flats with cutbait and it WORKS!

I recently hooked a big flathead using squid while fishing for channels with my channel cat rod. Couldn't turn it and barely slowed it down before it tangled me in a snag and I lost it . So now I know that flatheads will take squid as well. Wish that ole flattie had taken the live sunfish I had on my flathead rig about 20 feet away from my channel rig!

Yep live and cut bait works great. Way to go.

Small bullheads work real well for the flatheads also.