Which is the strongest?
 

I was reading the Sil regarding the Valar and I'm confused as to the strength and power of the Valar relative to each other. Melkor is said to be the strongest, but equal to Manwe. However, Tulkas is also said to be the strongest at one point. Who is the strongest and whats the line up of strongest to least strong? And what does strength even measure, they are God-like beings... strength of will, strength of magical ability?

In terms of actual physical strenght, Tulkas is the man!

However, there is much more to the power of the Valar than simple physical strength. Each was supreme in his or her own bailiwick, I suppose (for example, I don't think any of the Valar could have withstood Ulmo if they were caught in the middle of the ocean).

Their relative rank is listed in the Silmarillion.

- Cirdan / Maglor68

Melkor was the strongest when all abilities were taken into account; Tulkas may have beaten him in single combat, but had they been pitted against each other with Eä as the battlefield, Melkor would have used his other abilities and his mind to win.

Melkor was the smartest, and Tulkas the strongest physically. strength is a very general word and can mean a lot of things... i would say, that Melkor was the strongest, since it really took the whole of the Valar to go against him... and he arose against all the rest