120 or 240 AC current, Which one do you like best?

The main advantage of 230 vs 115 is that smaller size wire is necessary, or longer runs can be made with the same size. Fewer amps must flow for the same wattage of power, because the voltage is higher.

Whether it is 115 or 220 volts, don't attempt it unless you know what you are doing. 115 vac can kill you just as well as 220vac. A 220 volt line is just two 115 volt lines, connected to different phases of the 2-phase power input. Making a 220 volt line is like making a 115 volt line two times. Same skills. Same hazards.

If you switch over to 240VAC, you'll be in for a complete new set of PC's, since it's a different plug configuration. Also a different receptacle configuration. This is the deal breaker...

You will also eliminate the Neutral leg, thus dropping Common Mode noise problems. It will do nothing for Differential Mode noise potential.

You will reduce voltage drop concerns by half, but you've already addressed this with your new runs.

I don't see a scrap of upside to this. It's been already thought about and addressed by the balanced power devices that output + and - 60VAC. It's also been addressed by a separate Article in the National Electrical Code.

I'd look into products by Equi=Tech or Balanced Power Technology, etc. Those that are 3rd party listed by UL, CSA, etc would influence me even more.

I have no vested or uninvested interest in anything...

I am using US AC plugs on 220V - all you need is to ensure the outlet and plugs are compatible.

I have heard both 110 and 220, but in different rooms (w same components) and different continents ! To my ears 220 sounds superior - greater sense of ease. YMMV

My system uses a 30 amp, 220V dedicated line w/ a stepdown isolation transformer/filter. There's more beef...