I am toying with connecting via ethernet to save a USB space on my control computer.  I have also ordered an FTDI serial adapter to try that out.  Therefore I should only need 1 USB cable to my entire imaging rig.  What are your connections and why?

GTOCP3 here, so USB direct from my NUC-like miniPC to a 14 year old Prolific-based USB to serial adaptor that plugs into the CP3. Somehow, this old adaptor has managed to survive winters and summers outdoors under nothing more than a Telegizmos 365 cover and it still manages to do its job just fine. The only thing I've have do to in terms of maintenance is to take some pliers and pinch in the D-sub housing a bit so that it maintains a good grip on the CP3's female DB9 port.

When the 1100GTO that is on order arrives, I'll likely do direct USB. Same if I decide to upgrade the CP3 on my Mach1 to a CP4, but that's unlikely at this point in light of the pending arrival of the 1100. Ethernet's cool and all, but it's not needed for range (it's 1 wire-meter max. between miniPC and the CP's location) and USB will probably do just fine given my insistence on using non-trash cables and securing them such that the connectors never take any mechanical strain.

As for Wifi, there's more room for failure and there are a few special considerations, at least in my case. My miniPC's wifi is already on my home wifi network, so the CP's wifi radio would need also need be on the same SSID, thus putting all communication between my miniPC and the CP through one of my 2 meshed access points back inside the house. Additionally, the CP would be mounted on the south side of my pier and its transmission and reception would be blocked by the pier and mount as my house and the access points are to the north of my pier. ATS piers excel at many aspects of doing the job of a telescope pier, and I'm sure attenuating 2.4/5GHz wifi is also something that it's adept at doing. So I'm not going to go there. It just doesn't offer me any advantages over a ~1m direct USB connection.

I have an ATS pier as well, and that is truly a lot of metal near a WiFi antenna. Today I used google Remote Desktop for the first time, so I plan to have my laptop on the home WiFi and remote into that laptop from inside the air conditioned house. Alabama summers are brutal, 90+ degrees and 80% humidity is horrible. 

USB to RS-232 on a Mach2 (CP5) because I'm a creature of habit. I am in the backyard, but I don't need anything else. I don't trust WiFi in general and I have read that in particular the CP4/CP5 has drop outs. I have no need to run a cable (ethernet) all the way to the house. I DO connect to the PC via wifi so that I can control it via Remote Desktop.

None of the above.

I use the "Keypad" as my control computer as a visual observer.
For connecting another computer I have successfully used all the other options.

I have an industrial mini computer near the mount that has RS 232 ports that I use to connect to the mount.

Frank

I use USB to the CP5. I have an Eagle 3 mounted on top of my scope.  Its 12 volt power comes from the through the mount power connection, which it then powers all the devices.  The USB from the CP5 feeds into the Eagle through the mount. I use a tiny portable router which just sits on the Eagle using Velcro. The Eagle connects to the router via ethernet cable and I remote into the router via Microsoft Remote Desktop (the Eagle WIFI is not very reliable). It all works really well. 

I run NINA via ASCOM and TheSkyX via ASCOM.

Terry

I should have put keypad as a choice in the poll.

I use Ethernet for my Mach1GTO, CP4.  Through the mount cabling includes POE for my Optec focuser, a single USB3 for the three ASCOM devices, and a 12VDC for the cooler.  These go to a homemade, personally designed distribution box, then to my laptop.  Never a failure of any kind.

Negative. The CP5 is (currently) unique to the Mach2 because the CP5's motor driving circuitry is for running the unique-to-the-Mach2 brushless servo motors. The CP1/2/3/4 has circuitry for driving the "classic" servo motors that are in the rest of the GTO line, past and present.

You can't even accidentally do this because the CP<=4 classic servos connect with a single connection, where the Mach2+CP5 has separate connections for RA and Dec motor and, if memory serves, the gender and keying of the connectors also differ.

I use Ethernet with CP4 and Optec Focus Boss II along with Ethernet 5 port switch. 

https://peternagy.smugmug.com/Telescopes/Current-Equipment/i-BmcNW77/A

Click on left and right arrows for more pictures.

From back to front:

CP4
Optec Focus Boss II
Ethernet 5 port switch 
Pegasus 6 port USB hub

Note blue Ethernet and USB cables inside braided loom at lower left.

Peter 

Ethernet for Mach1/CP4 and Optec Focuser.  Camera control and guide scope are USB.

Photos of my setup: