In addition to the recommendations in this forum, you could check Consumer Reports for their recommendations.

Another possibility that could work would be to ask a respected, experienced realtor in your area who they send new homeowners to for appliances, and then follow the recommendations of that person.

The local Chamber of Commece might also be able to recommend a reputable dealer in your area.

When I was looking for a new microwave recently, none of the big box stores had as large a one as I wanted, and it was only the smaller dealer in appliances we usually go to that had what I wanted.

The smaller dealers are also often better at helping you to install your appliances.

More information would help people give you better advice. Size constraints? Do you have gas? Features you want?

I'd suggest looking at Bosch dishwashers (what I have and am very happy with) or if you are prepared to pay more Miele (usually highly recommended here).

For the cooktop, I suggest exploring induction. I went with induction over gas in my range a little over a year ago based on my research, mostly here. And I love my induction range!