Not sure what you mean by power filters, but as for what you need.
1. Great skimmer
2. Heater
3. Good circulation via powerheads or closed loop system with one main pump
4. Good lighting (dependent on what you want to keep)
5. Filtration system (LR/LS, wet/dry filter, canister)
6. TEST KITS!!
7. RO/DI water
Now those are the essentials, many people go beyond as you will find out sooner or later (expensive hobby). Phosphate filters, kalkreactors, calcium reactors, algae scrubbers, battery backups, auto-topoff, refugium(may also be an essential), etc.
A sump is just a holding place for heaters, skimmers and such. Hides the uglyness of all that equipment.
Good Luck!