Kind of an old thread, but I've had good results with Universal, which is red colored and which I can see when I look down into the shell while it's still in my Hornady LnL.

That said, I do like Trail Boss. It gets used up fast, but it's pretty much idiot proof. Even a minimum load will fill the case plenty to see. I load it to the recommended max in .38/.357/.44 mag.

The only powder I've had a truly bad experience with is 700x, which meters like a loaf of bread in my Lock and Load powder drop.

You might look into a mid-range powder like Longshot, CFE Pistol, or SR 4756. Because they are slower (but not as slow as 2400), you can use a larger charge that should make them more visible. 800x is another possibility but meters legendarily poorly (I haven't tried it). Also, using lighter bullets allows for a larger powder charge which might get you into you comfort zone.

Something to bear in mind, though, is to get most of these powders up to where they fill the cartridge, you'll be using max loads. So they will be hot!