6061 T6 will work, but 5052 has more options for welding it "correctly".
6061 T6 was developed for designs where it is used as a structure (think airplane or bridge) as opposed to simple tank designs. As such the ksi is higher and is limited in weld consumables.
5052 can be welded with 4046 wire which is most common. If 6061 T6 is welded with 4046 wire, the welds will crack over time from flexing. I've seen it happen on box structures simply by moving it with a forklift.
Bottom line, yes, you can use 6061 T6, but make sure your fabricator knows the correct wire to use for the application.