Like pretty much everyone else here, Shephard's Mind is my favourite after FM. I also like all of the other "Master Mind" series (Barney's Mind, Felix's Mind, Chell's Mind, Harrison's Mind, Parker's Mind, and Freeman's-ish Mind). I've also enjoyed a few others, like Isaac Clarke's Mind, Declan's Mind, and some other Mind series-type stuff put out by a Youtube user called dragonv0942 (none of them are actually called "So-and-So's Mind" like the rest, and they're generally more serious, but they're good and it's the same format). None of them will really have the same spark as Freeman's Mind, but they're all good in their own way and well worth watching.