Congratulations on your first rig and welcome to the community!
There are two leading down-converter manufacturers. One is Decimator2 manufactured by Decimator Design. It’s a very reliable unit, very wide voltage range as well as an additional HDMI output with scaling capabilities. The only downside is although the unit is guaranteed for 36 mouths, if anything goes wrong the turn-around time could be a little long. This is the one I own.
The other one is Blackmagic design’s down-converter. This unit also is highly acclaimed but if you go and buy a second hand one; be sure to check that it’s the new version. Old versions input voltage range is very narrow and the unit has tendencies to be burn if unregulated power is fed. There is also a version of it in a tougher casing which translates into additional weight.
Both DCs are priced very closely.
The best value for your money will be a used Analog Bartech unit. They are pretty much bullet proof and Jim is excellent in taking care of his customers. But be careful of the motor accompanying the BFD. M-One –which is a great and powerful motor- is de facto no longer supported by its manufacturer Loom works. So your motor won’t be repaired if anything goes wrong until Loom Works gets its head back in the game or someone else starts servicing these motors. So it might be a better idea to buy a Heden motor BFD set.