suggestions needed to choose some kits

Dragon for all of them. I believe they rereleased their Stug IV Late. Try Greatmodels, they have a new policy where they match any competitors prices.

Italeri makes the stug IV and I believe that Tamiya doe's also. I have built Ital's and its not a bad kit but it doe's need work. I am actually building Fujimis 1/76 scale Hetzer right now and its a decent kit though its missing a few details but I'm assuming your looking for 1/35 scale.

I would recommend the DML versions of the Jagdpanzer IV and the Hetzer. They both have good detail and come with extra parts. The hard part might be finding these kits as I think they are oop, but still can be found on Ebay. I have partially built the DML
Stug IV and had nothing but troubles. I don't know if anybody else makes this kit.