'Strictly Personal' is slightly more experimental than 'Safe as...', but keeps that bluesy feel. 'Clear Spot' (my fav) is also pretty out there, but very accessible. His album with Zappa, 'Bongo Fury', is also very cool.
I will be shot for mentioning this, but his 'commercial' album 'Unconditionally Guaranteed' is a fine album. Most Beefheart fans hate it due to its 'simple' and poppy song structures, but it's an album most artists would love to be able to write.
'Bat Chain Puller' is also fine, he had a new band after a hiatus and the album sounds really fresh.
The secret to 'Trout Mask...' is to listen to it again, and again, and again, and again ,and again....and again...and again...........then one more time...then, and only then will you get it. After that you will be ready for his true masterpiece 'Lick My Decals Off, Baby'. It's worth it dude, I promise