I am a more of a death-metal person.  I respect your opinion and I hope you respect mine.  But, I do see a lot of people not liking other types of music.  Personally, I cannot stand rap music or pop.  But, I guess it's just the family I grew up around.  Bunch of metal heads!  

Metal all the way. Power metal, progressive metal, heavy metal, and melodic metal are all my favorite genres.

This is easy, metal most definitely, I grew up on bands like Slayer and GWAR so metal is kind of like a first love for me. I love Punk a lot too, but that R'n'B stuff no thank you. I can't listen to that stuff, it is all chorus. What I hear when a song like that comes on is either a song full of chorus that is meant to get stuck in your head or a song about some kind of break up or first love or something like that. I am not bashing the style please everyone do not misinterpret that, I don't care at all if anyone listens to it, just my personal opinion is all.

I'll have to go with Metal. I'm only half sure that I've ever even heard RnB. As for what type of metal I like, I don't really know. I've only heard one group, and that was Disciple.

I will go with metal, too ! Heavy metal, melodic death metal and thrash metal are my most favourite

Pretty obvious don't you think? Metal of course. lol i love death metal and black metal. But also thrash metal.
i dislike metal core. Screaming girls and some half plugged guitars..
but a couple of death core bands do have some talent with them. Even though i don't like it lol.
my favorite genre in metal would be technical death metal and symphonic black metal.
but also progressive death/black is cool.. Just like melodic or fusion (like atheist and cynic)

my favorite bands would be:
Death (80's old school death metal) ( first technical death metal)
cattle decapitation (death metal with anti humanity lyrics)
fallujah( technical death metal with a bit of death core influed)
psycroptic (technical death metal, progressive death metal
obscura (technical death metal)
beyond creation (technical death metal)
gorod (progressive death metal, technical death metal)
fleshgod apocalypse (technical death metal)
hour of penance (technical death metal , brutal death metal)
mesuggah (progressive death metal)
decrepit birth (technical death metal with old school death metal infleud)
Of course i do have ALOT of other amazing bands i like a lot.
but this is kind a my main i think.

I honestly have to say I own a ton of Metal C.D.s.
That Said...
I Respect both.
BUT.
I wish the R&B radio stations had a little more variety. Hearing the same 10 songs for a years worth of time is mind numbing. The line-up changes only yearly.
With the Metal Stations you get a ton of stuff throughout 30 to 40 years.
R&B is not one year old.
That aside.?
I go with Metal because you just need a couple of guys and their instruments to hear some music.
R&B requires a Studio, a ton of Cash, and at least One Person with a Voice and a Group of Backups?
The genre of R&B needs a kind of rebirth every 6 months these days (in my opinion).
With Metal it is clear that it needs no help to survive the years of punishment that the "trends" can unleash on it (again, my opinion).

Here is an R&B cover done by a Rock/Metal band. It mixes Evil with Passion and works quite well. ("Far". "Poney".)

http://www.youtube.com/watch?v=hgPwx0DjrWw

Another tune that makes everyone go wild with a Devilish Grinn. In a different category (Rap and HipHop Covered by a metal group). Is "Throwdown" with "Baby Got Back".
(I am not going to provide a link this time.)

The point is All Genres of Music have their Place with Longevity.
The Major Differences??
R&B gets Played out and Metal gets Burned out.
With Metal the chances for it (any single song) making a comeback is Better and more frequent.
With R&B the chances for it (any single song) making a comeback is Slimmer and less frequent.
I have no idea why.
It just is.

For me I go with metal. I do not need the cash to play my guitar and write a song.
For R&B? I would need a ton of cash and equipment.

Metal swings my vote.
Good Luck To All.
I'm done. Stick a fork in me.
Peace.

Me personally, I like Metal more than I will like any other genre. Metal & rock have influenced nearly every other music genre, there's more variety [ at least, in my opinion ] and it takes a whole lot more talent to write a song for a Metal album than it is to come up with an R&B song. I've grown up with metal, and while I do like other genres; metal has always been my favorite~

Personally I listen to more metal than I do RnB.
So I would have to give my vote to metal, thou there are a few RnB songs that I don't mind listening to.
But in terms of numbers, metal songs beat the number of RnB songs I enjoy.

I like R&B better only because metal is just people screaming and really look unnecessary noise.

I like R%B more. I have never really been a fan of metal because it kinda hurts my ears sometimes.. more like screaming and crazy noisy. I have tried to listen to many metal artists and I just can never find one I like.

I prefer metal out of the two, just not a huge fan of R & B to be honest.

Metal is where it is at man, though I do like certain R & B here and there.