Not sure if you ONLY want suggestions for a seater or the full die set.
Most any seater will do a good job for you but nothing helps straight seating more than a straight neck and nothing helps that more than a good expander. Lyman's M expander is, IMHO, the BEST expander die design on the market. Get a set of Lyman dies and see!
The design purpose of the excellant Lee/Hornady collet holders for their decapping rods is to better hold them in line with the die body. Works pretty good too, but does require really torquing down on the collets to hold the rod securely. Welding the smooth decap rod in place will certainly keep it there but will also make cleaning the die somewhat difficult.
I just take a threading die and cut bolt threads on those rod tops, then a machine nut serves to secure them in place. Think it takes a #10 thread for most of them.