Most techinical

Most of them are. All of the solos are and alot of the rhythm and lead parts during the verses/choruses etc. There's not really any point arguing about "the most technical" when you're referring to Children Of Bodom.
 
Warheart is right but imo, the solos in KtS is downright hard. It's terribly difficult to make it sound good cause it have to be perfectly accurate,especially the last run of the last solo ( which I can't)
 
Kissing the Shadows has some uber technical solos. Toward Dead End is not so much technical as it is fast. Lake Bodom's intro and solos are reasonably techy, along with parts of Red Light In My Eyes pt. 2 and parts of Deadnight Warrior.

If you're looking for technicality outside of CoB, however, Cacophony is a must-listen.