Is it a gas leak (turn off the gas!)
or a water leak.
Any plumber can deal with the water leak whether it be soldered copper or flare/compression fittings. They will tell you if they are liscened and bonded for whatever system you have. There is a plumbers reccomendation thread elsewhere in these forums.
I do my own.
Is it leaking where you can see the pipe? Is it leaking at a fixture/radiator/ PEX hose? In side the wall?
Do whatever is necessary to stop further damage/danger while you shop around.
For replacement and re configuration I used Brennan. No complaints but they were not the cheapest bid. I threw out the cheapest bid based on word of mouth and it seems others on this forum have the same opinion of a local company.