Keep in mind that people have different mouse grips, which is part of the subjectivity in "comfort." I personally use a grip between claw/fingertip for precise control and to prevent wrist stress, which means I find highly compact mobile mice perfect for even desktop use. Mice like the Wedge can only be used in the fingertip grip. (There are guides out there describing the mouse grip styles and advantages/disadvantages. It's also very possible to retrain oneself into a different mouse grip, FYI.) Personally, especially if significant mousing will be involved, I think it's more important to get the most comfortable mouse first and worry about price/connection type second...
Though it is true that one can change to a different grip, I do believe there is a natural grip/position that works best for the human hand, just as high heels probably aren't the most comfortable shoes for people even if a person could get used to them.
In the case of having a surface pro, connection type is pretty important as some people won't want to have the hassle of always having to remove the usb dongle every time you need to use the usb port for something else. So I bought a Bluetooth keyboard and mouse so that the usb port is always free and ready to use.
whats most imporatnt to me is the bluetooth mouse works as soon as you touch it everytime. ergonimically over last 25 years ... i've used every known mouse on the planet and just want them to work well first ... feel good second.