I have the 3320 with e-hydro. I mostly use the 300 cx loader which does everything I ask it to. I also use a finish mower for which the e-hydro is great, you can ease around ditches, poles and other obstacles while keeping your rpm's in tact yet slowing the ground speed for getting around.
I wouldn't even think about not getting the e-hydro. The only scenario I could think of in getting the regular transmission is if you planned on doing mostly all heavy pulling or tillage work where variable speed didn't make a difference because I do feel you give up a little power with the hydro.
However, for mowing or loader work, the e-hyro, in my opinion, is the only way to go. The 3320 will have sufficient power for any loader or mower work as long as you stay within the recommended range of implements. I have a MX6 rotary cutter I bought for another tractor that will also work on the 3320, but if you get into 3 foot grass, it will slow you up a bit.
I also looked at the 3203 (for about 2 minutes) but disregarded it because it is so stripped down. The 3320 has a few extra horses than the 3120 and for not much extra money, here in south central Illinois it is less than $800. The 3320 is the most popular in this area because it has the largest block and no turbo. You pay dearly for those few extra horses when you get to the 3520 or 3720.