Of course they aren't all equal. They even use different sensing methods, and we've seen that non-sensor people can sense strong chakra as well, so this ability is something everyone possesses to some degree, but some are more sensitive from birth (presumably), some can probably learn it etc.
Say, we know that Karin's skill is unique, it even has a name, while sensitivity is apparently genetic in the Yamanaka clan. Naruto gained his sensing skills from SM/KCM/BM, Tobirama and Minato can use that finger on the ground thing while C uses hand seals to sense (unlike say Ao), which might imply that he learned it instead of being sensitive from birth.
Anyway, I think it makes sense for the Senju to have innate sensing abilities since they have the "body" of the Sage, and the Sage had Juubi which can also sense chakra (it showed it while in tree form). So it's pretty safe to assume that Sage was a sensor too. Uzumakis, well, they were too related to Senju (as per manga).
Otherwise it's hard to compare sensors. Which factors can be considered? Range? We haven't really seen most characters to use their sensing abilities to the max, so to say. Only Naruto and Karin's sensing abilities were actually shown in sufficient depth, I think. Ino has shown the ability to "lock on" targets, but we don't know how much of a feat it is. Ao was made head of the Sensor Division, so I guess he can be considered to be skilled enough for that. So... They aren't simply not equal, they are all quite different I'd say.
And also, sensing skills have been often used as plot device so sensors basically can do whatever is convenient for Kishi at any given moment. With all this I doubt it's possible to say what defines the "best" sensors (well, apart from SM/KCM/BM Naruto who can sense anyone anywhere plus negative emotions/hearts/whatever).