Ralph Sawyer would say his translation is the best, and that you should buy it, and probably something about China attacking Japan, if you asked him (he's a very intelligent and friendly man, but has some very strong opinions).

As for differences, some translations place different sections in different places due to disagreement on which bamboo thing goes where, certain translation choice, and understanding of words in their context at the time.

Honestly, Guiles is still relevant, but beyond his and Sawyer's work, there have been some fairly good translations by Chinese scholars, which, while they tend to read fairly awkwardly to a native English reader, are likely more strictly accurate.