I love Something Wild the most musically. The musical onslaught of Deadnight Warrior, In The Shadows, Red Light In My Eyes, and Touch Like Angel of Death, and you can't forget The Nail or Lake Bodom. This album is one of the most perfect metal albums ever concieved.
Follow the Reaper has to many good memories in it so it gets my vote for best. It had an impact on my life that no other metal album will have. Highlights for me are Bodom After Midnight, Kissing the Shadows, Everytime I Die, Hate Me and Northren Comfort. It is also the most melodic in my opinion.
Hatebreeder is overrated and my least favorite, but still a good metal album by far. Can't go wrong with Black Widow and Downfall though. Warheart and Bed of Razors get old fast, the rest of the album is killer and nobody seems to really gives a crap about Wrath Within which is a very good, overlooked song which kinda feels out of place on this album.
Hatecrew Deathroll is their most brutal album and I have no complaints and it has Triple Corpse Hammerblow on it which is probably my favorite Bodom song, not sure on that though, I like em all equally for one reason or another but if I had to pick a favorite it would most likely be that or TLAOD. Sixpounder, You're Better off Dead, Angels Don't Kill, and Chokehold are my other favorites, I think Needled 24/7 is CoB's weakest song, but it is an awesome song to hear live, and still a decent song to listen to.