<font color="green"> The tractors I have found that compare best to the JD 3320 are the New Holland TC33DA, Kubota L3400 and Kioti CK30. </font>
cart99 . . . For what it is worth, I'd like to make a slight modification to your list. The Kubota L3400 is one of their budget tractors, comparing it to fully featured tractors is really going to make the L3400 look pretty bad. It has power, but not features.
The Deere 3320 is 32.5hp, 25.5 PTO hp, weight = 2900#, 3pt lift 2500#+
The Kubota L3130 is 32.1hp, 25.5 PTO hp, weight =2750#, 3pt lift 2200#
The Kioti CK30 is 30hp, 24 PTO hp, weight =3040#, 3pt lift 1765#
The NH TC33DA is 33hp, 28.6 PTO hp, weight = 2590#, 3pt lift 1635#
From the above specs you can probably tell that these are still fairly different machines despite some similarities. The TC has the lightest weight and highest PTO power, but lowest lift capacity. The CK30 has the heaviest weight, lowest PTO and slightly more lift capcity. The JD and Kubota both are significantly greater in the 3pt lift capacity with the JD leading by a good margin, and offering similar PTO power.
I did not compare wheelbase dimensions, largely because they are misleading as they do not seem to relate to either overall size or turning radius, the TC is the smallest and tightest turning with the SuperSteer option, the CK30 and L3130 are within 2" of each other for L.O.A. with the L3130 topping out at 124" without loader.
Now in terms of features the L3400 doesn't really match up to the above machines, but in terms of the specs above it has the following:
34.7hp, 29 PTO hp, 2400 weight, 1435 3pt capacity
Clearly 2 of the machines have more capacity than the others in terms of lift. On the other hand, a different 2 machines have more available PTO power than the others. So if you want a high weight capacity machine, choose either the JD3320 or the Kubota L3130. If you have PTO implements that require more power, the Kubota L3400 and the TC33DA are the clear winners. All this assumes price is no object. The L3400 is going to be a lower price, as is the CK30, so when budget overrides other issues, those will likely be the choices (realizing pricing is regional).