I have towed surge and electric/hydraulic both.
Surge is ok if you always brake in a straight line.
But if you get into curved roads or worst case scenario- trailer trying to pass the truck around the corners-- :-0
The electric over hydraulic are best.
The straight electrics are ok but I hear they don't survive well if dunked in the water.
The electric controller is great because you can "dial" the amount of braking that you need for the change in load. Plus you can select brakes on trailer without utilizing the brakes on the tow vehicle.
This ability is critical if the rear of vehicle would get into sand/gravel/oil covered road where the trailer tends to push the rear of the truck around.
SRW or DRW is preference.
Mine is DRW because the rear does not seem to sway in cross winds or in corners as much as SRW.
But if you have a DRW truck, the truck has to be loaded heavy enough for both the rear wheels to dig in when needed. Nothing slides or skips across cupped or unimproved roads as bad as a duelly without a load.