In my opinion it all depends. Do you have sump only for filtering and allocate most of flow to power heads? If so, you don't need a lot of flow from the sump. It is burning money in my opinion if you have too much flow there. I think sump is for keeping your gear and filter there and put some water flow to mixed the output with DT water.
What I would do is go with DC pump for sure. You have a regulation of the flow in the controller so you can dial to whatever flow you like. I dialed my controller to visually see water flow but not to make a white water rafting in the sump. And what is the good water flow from the sump? You will feel that, just use your common sense, don't look at numbers.
AC pump you just turn on and you have what the pump gives you. It is difficult to match pump from the paper to your exact setup. How high does it have to pump? How long are the pipes? how many angles? Etc. A lot of factors and if you decide to upgrade your tank you will be stuck with this pump.
Which pump? In my opinion the cheapest - Jebao. I used to use Jebao DCP-2500 (660gph) in my 75g tank and I had it on like 30%. Now I use it in my 240g tank and its running on 100%. $52 on amazon. You can replace it each year if you are religious about gear (I am not). If you go with quality pump you will spend $250 and it can still break in a year. I would put more money in corals or fish instead of fancy gear.
It is funny and annoying with the gear. You have no idea what you are dealing with before you use it. Once you start it in your tank you have a good understanding what is what, how to use it correctly and how to make things easier.