They're all pretty much OK.

Sora - if you can reach the thumb levers and don't have a problem with them, or the whatever-speed, it's OK.
Tiagra - pretty good group but, unless it's changed in the past year, is 9 speed only.
105 - Good group, 10 speed, so compatible with higher level stuff.

In general the only things that aren't compatible between the three are the shifters and cassette, they need to be changed at the same time due to the different # of gears.