Just off the top of my head- nechryael. Great exp, drop a fair amount of snapdragon seeds, rune boots, rune full helms; with guthans or a bunyip + sgs you can camp forever; they definitely don't cost any more than dust devils. Plus they have a solid 33%+ droprate of crimsons, which is way better than the 20% I seem to get from dust devils. You've also got waterfiends at higher levels, which drop EXTREMELY well, are not really that much harder to kill than other monsters when you're well-equipped, have an EXTREMELY high crimson droprate, and are easy to get back to from banking. Once you've been there it feels kind of silly to camp dust devils. Yeah, unless if it is fun for you :P