I didn't mean that you are a hater of it, btw. Firstly, I'll tell you about them. Opeth is an extreme progressive metal band. They've released a fair few albums which are a mixture of heavy/light stuff and they've released one completely mellow album called Damnation, which I recommend to Opeth beginners.
I'd describe Opeth as Beauty and the Beast. They have very heavy parts with great riffing, good death metal vocals and insane drumming. They also have beautiful parts with acoustic guitar riRAB, clean vocals and nice keyboard work. It is not unusual for Opeth to have long songs with acoustic and electric guitar work, growling, clean vocals, double bass blasts etc.
The vocals are outstanding. The basswork and guitarwork is very good too. The drumwork is always interesting (which is saying something coming from someone who doesn't listen for drums) and the lyrics are great.
With that said, Opeth is progressive music centered around song structure. Very few of their songs are shorter than 10 minutes. If you don't like progressive music, you might not like Opeth, but I'd give them a try anyway. Start with the completely mellow Damnation album. If you're after particular songs from their whole career, I would probably try Windowpane, Bleak, To Bid You Farewell, the Drapery Falls, the Moor, Ghost of Perdition and possibly Credence. Chances are that you'll have to give them a few listens to like them. If you don't like the harsh vocals, you'll get used to them. I'll try and get around to actually uploading the songs somewhere. I can recommend you songs that have good examples of particular things, i.e. drumwork, acoustic work etc.
Remeraber, a good attention span is critical for listening to them, otherwise, you may not be doing yourself justice when you listen to them. Opeth songs are much better when you listen to them as a whole.