I run a couple different setups. On the ST I have a SmarTire setup that is no longer available according to some sources but I still find them on sale from time to time. The sensor is held to the center of the rim with a huge band clamp which lets you do whatever you want with the valve stems. The display runs off the bikes power and provides the standard feature. No issues with it for several years. On my KLR I run TireGard because of the tubes which means no sensors in the wheel. Sensor mounts to the valve stem and has a locking collar keep it in place. I like the key chain display because I can put it in a pocket or tank bag. I usually just use it to check the pressure before I start my ride or when stopped somewhere. I wouldn't use this type of setup with rubber valve stems as the extra weight and higher speeds could cause the stem to fail. I also wouldn't use it with angled stems either as it would probably stick out too far. I haven't really tried them to see but just a possibility. Not on the bikes but my truck, I have an Orange Electronic retrofit kit. It is the conventional setup with the sensor mounted to the valve stem inside the wheel. I opted for a cigarette lighter power plug on the display for simplicity. My only complaint with this unit is the display is not very bright and hard to read in direct sun or when very bright outside. This too is an older unit and I've read the newer displays are brighter. Other than that it's been flawless. Orange Electronics also builds a MC unit with sensor mounted to straight stem like cars. I just wish they had an option for angled stems.
It pretty much boils down to the configuration you want to run, try and go with one with longest battery life for the sensors, and how much money you are willing to part with.