namekian vs sayain (no buu's)

I don't think so and it depend on gear.

Humans/Saiyan can do fast combo and dodge but they're very squichy and you have in the other side Namekians with high defence and less damage/speed than human.

I give you an example :
Namekian SK with 1 bold stike can kill a fighter but fighter can also dodge his attack and 1 shot SK.
Fighter with 1 click can kill SK but SK can also block/tank the damage and 1 hit fighter.
Or they can die at the same time just like in the picture

and also kappa fighter can easly defeat kappa SK.
The best player on DBO was a human female turtle which makes your theory about Namekians being the best wrong

Meanwhile it depends on gear

I destroy Op SK and average fighters with my crane level 70 cap it all about gear and strategies. I learnt the best strategy at end dbo so I couldn't really use it to many times but when I did it awesome because other players would see my class and think I'm easy match up. If I had CCBD level 60 gear +10 I would of been unstoppable.

Namekians are the strongest, only if you don't count anything other than skills.
Because in DBO, gear is nearly 75% of what the game is about, 20% is for strategies, and 5% is skills.
But if you combine these three together just the right way, you basically can defeat ANY one in your way!
Some people use the gear to give higher Physical Attack power, use thunder as the skill, and just leave people to suffer with him punching them without damaging skills. Others depend much more on skills, such as cranes BTD (Burn to death) just like how Adrian said in his reply. He also said this "If I had CCBD level 60 gear +10 I would of been unstoppable." which is as I remeber is a Hero type of gear (the green colored)! and it is VERY broken in level 60 and 70 especially, because in other levels it is not (SO) much, but yea, he would've been actually Unstoppable!