A few questions

I have been using Promash for ages and now I'm trying all the others so I can decide on an upgrade soon. So far, I like the functionality here, but I have a few things that bug me visually.

In recipe, the grist and hops are in one big box, can they be separated into separate boxes?

Related to that, I would much prefer a separate time column for the hops instead of having it lumped in with the hop name. Same for Alpha percentage.

I know many folks like the many tabs and buttons on top, but I prefer as streamlined as possible. Some of them are even redundant, like the top menu bar has many duplicates with the tabs (I have hidden the menu bar). I would love to either minimize them or customize them so I can only see what I care about (tools, save, undo, print). The rest is available in other places on the screen, such as ingredients all being next to the ingredient pane, which is perfect.

Equipment profile and mash profile: I created my own equipment profile, can I somehow make it the default and not have to select it each time? Similarly, I only see myself needing three mash profiles, my equipment stays the same so it's just light, medium and full body. Can I move selected mash profiles permanently to the top of the list?

If these were addressed, this would be about perfect for me. Brewtarget has a look I like, but there is some functionality missing, Promash works great but is very dated.

Afraid I can't address many of these, but there's two I can help with.  Under 'options', you can select a default equipment profile.  Then you won't have to select it every time.
I don't know about moving mash profiles, but you can delete the ones you don't use if you like.

I too was a long time ProMash user that has converted to BeerSmith.  The two programs are very different in their layout and even where to find things.  From my experience and my advice, you have to go into a new program with an open mind and not try to recreate the old program.  I got stuck on this for quite a while, myself.

In the Design Tab, anything that could possibly go into the beer goes in this box.  Grain, hops, water profile, yeast, specialty ingredients, etc.  The idea here is to streamline all ingredients in one place.  I know that Brad is working on some enhancements to this ingredients box, adding the time and AAU columns is a good idea that maybe he can work in.

As for the top ribbon bar, you could change it to the small size so it is not as so distracting.  There is a lot of redundancy between the top ribbon bar and the side bar, but after a while you will get used to the layout.  It is a great idea to add into a future upgrade the ability to choose what is displayed in both of these bars.

Equipment and mash profiles, you could get all the ones you use set and delete the others.  To set up the defaults for a new recipe, open up a new recipe and get your equipment/mash profiles and options set how you want.  Do not add any ingredients or anything.  Then click the "Set As Default" button in the top ribbon.

The other great thing about BeerSmith, through this forum Brad is very active and listens to all requests to help the program to keep growing and getting better and better.  I hope you are able to get it to work out for you.

Cheers!