For Torpedo Bombers (TBs), go UK.

Why? -> http://fm.en.kupaisky.com/Community/Forum/View.aspx?num=9566&searchtype=0&pagecount=0&searchvalue=&sort=5&category=D01&page1=3

For Dive Bombers (DBs), I would say SN or IJN.

SN bombers hit a bit harder  than IJN ones, but they are a bit slower.

Just remember. Dive bombers are, damage-wise, more powerful than torpedo bombers. By experience, I could say that torpedo bombers sacrifice damage for mobility.

Ex: If your team completely dominates the airspace (or your fighters have complete control and can beat the enemy fighters), dive bombers would be the better choice. Dive bombers CAN evade fighters, but that isn't getting them anywhere (manipulated CoD). 

Torpedo bombers work excellently in this case - you can force them to juke-bomb to evade fighters and get to your target easily. However the damage isn't really impressive as compared to a full dive-bomber run hit.

Pick your poison. Damage, or mobility.

Maist. You are forgetting one thing about evading fighters with TBs.

If you cancel the bombing run they will automatically go back to max height and if someone uses 2 groups of fighters and microes one of them to follow your TBs at max height he will likely shred them.

As for the OP.

DBs:

USN - Fast bombers with high DP but somewhat weak bombs. As a bonus they look like USN fighters.
KM - Better bombs than USN but pretty short on fuel.
IJN - One of the better bombers. Pretty fast with very strong bombs.
RN - Best bombers but worst bombs (seriously their DBs have the most speed and armor of all T2 DBs).  
SN - Slowest bombers with good armor. Probably best bombs. 
MN - All around average in everything. BUT they get their T2 DBs several levels sooner. 
RM - Their DBs seem to be all around terrible.

TBs:

If you want to use TBs only take RN.
If you want to use TBs and FPs take either RM or USN. 

umm uk tbs are great but ur obviously forgetting ijn tbs as ijn they tend have most fuel and best torps with great mobility i always tend to devastate with them i do use manual tho