FWIW, KZ owner here... Of the two, go with the Jayco.
First thing is - inspect both frames closely. KZ uses a frame that has I-beams made from 3 pieces of sheet steel welded together. This type of frame is much more flexible than the more common one-piece beams and can lead to issues. Jayco uses a Norco/BAL frame which is far superior and stronger.
The Connect has a cargo carrying capacity of 1390 lbs and the Whitehawk is 1725 lbs. The Whitehawk has a higher GVWR for about the same length of TT. The difference in the frame is a big factor in this. A CCC of 1390 lbs is on the low side and you could very well use it all when fully loaded for camping and it's possible you could even be over the GVWR if you don't weigh the TT and watch what you add (a full holding tank could even put you over the GVWR).
Look at the tires. Whitehawk has Goodyear tires (should be the new Endurance) while the Connect will have an off-brand unknown quality Ch*nese brand. KZ used to offer an upgrade to LRD Goodyear Marathons (which we have) but don't see that offered now. Also look at the load capacity rating of the tires. The Endurance tires most likely have a high load rating compared to the TT GVWR while the Connect likely has tires that are loaded up much closer to their load capacity rating. (You want as much reserve load capacity rating as possible to reduce the risk of a blowout.)
Another thing to possibly look at is the rating of the axles. I think you'd want 4400 lb axles on the Connect and maybe 5200 lbs on the Whitehawk. Axles loaded up closed to their ratings are more susceptible to bending & damage.
The Whitehawk has a few features I like better such as an easier to see TV from the seating due to the angle it's mounted at, walk-in shower and larger pantry. A MAJOR drawback in both of those TTs is the lack of a wardrobe closet. Where are you going to hang jackets and store misc. camping stuff & misc. supplies?
Why not look at a Spree S333BHK? Other than the kitchen island & slide, I'd say it's closer to a Whitehawk than a Connect in features. A Connect & Spree are the same basic TT and the Spree is the more upscale version with more features and the Connect is a more stripped down version (reflected in it's lower GVWR too).
Something often not considered is the "quality" of the dealer. There aren't many good ones out there that know how to properly make repairs and do warranty repairs and that don't argue about warranty work or try to avoid it altogether. Our KZ dealer was a disaster.
Always ignore dry unloaded weights. They are meaningless and always go up. Without being able to go to a scale before purchase, use the GVWR figures. You'll add 1,000 - 1,500 lbs and possibly more to the UVW.
What are the truck details? Both of those TTs are very looong. You should tow either TT with at least a 3/4 ton TV. "Tow capacity" is not what you need to focus on. Payload capacity of the TV is the important number and is extremely important. The Whitehawk will have an actual tongue weight around 1200 lbs (12%) and could even be higher at about 1300-1400 lbs (15%). The weight of passengers, pets, groceries, firewood and misc. camping stuff can be in the 500-1,000 lb range which must be added to the tongue wt. On the high side, you could be looking at over 2,000 lbs of payload and the TV needs to be rated to handle that. You *could* take the truck to a scale to find it's actual payload capacity but I doubt it's anywhere near capable.
The Whitehawk will have an actual tongue weight around 1200 lbs (12%) and could even be higher at about 1300-1400 lbs (15%). The weight of passengers, pets, groceries, firewood and misc. camping stuff can be in the 500-1,000 lb range which must be added to the tongue wt. On the high side, you could be looking at over 2,000 lbs of payload and the TV needs to be rated to handle that. The Connect TT will of course have a lower actual TW.
It's always recommended to take a TT to a scale to get is's actual total weight (GVW), actual tongue weight and payload capacity. WDHs can also be fine-tuned at a scale. You'll need a good, properly rated and properly installed WDH.
The Whitehawk will have an actual tongue weight around 1200 lbs (12%) and could even be higher at about 1300-1400 lbs (15%). The weight of passengers, pets, groceries, firewood and misc. camping stuff can be in the 500-1,000 lb range which must be added to the tongue wt. On the high side, you could be looking at over 2,000 lbs of payload and the TV needs to be rated to handle that. The Connect TT will of course have a lower actual TW. It's always recommended to take a TT to a scale to get is's actual total weight (GVW), actual tongue weight and payload capacity. WDHs can also be fine-tuned at a scale.
Use a WDH that has integral sway control and not add-on friction bars. Minimizing/eliminating sway will be more of a challenge at 37'+/-. There are a number of factors that contribute to sway control that need to be addressed and you should learn about them.
Do NOT let a dealer or hitch shop install a WDH. Learn how to correctly set it up and fine tune it yourself.
Choose wisely and don't forget to post your decision!