Is there a difference between having the muffler welded to the exhaust pipe or having clamps?

I go through a muffler every other year.  I know condensation goes through the exhaust but I always have an issue with the portion of pipe that goes into the muffler - it rusts and pulls away.  I had another hanger put on the last muffler change to try and hold it tighter but it still does the same thing.  They are just no name cheap Turbo Mufflers but I don't weld so if clamping is just as good I can replace them myself. 
Another tidbit - I am currently changing my head gasket so it is possible I had a very small pin hole leak into the exhaust that contributed

Any reccomendation on a better muffler or one that holds up to condensation better?

Clamps work great if you get the right ones, I like the band style clamps, they are used on heavy diesel exhaust systems. You just need to make sure the pipes slide together all the way before putting the clamp on. 

Much depends on the type of piping your using. I used aluminized tubing for my exhaust system and have had no rust whatsoever, I also use a cheap turbo muffler. I do use clamps just for the muffler, everything else is welded then painted over with High Temp ceramic paint.

work at an exhaust shop. most times clamps fail. either to tight and crimp and leak or to loose and pipes dont hold. also the joint needs to be a tight fit to get a good seal.

i know with the shop i work for a clamp is never used without 2 inch long welds on either side of the pipe to stop leaks.
if its something we arnt sure is going to be a good seal we just weld it solid. welds are easy enough to cut off if it ever needs to be done.

there are several grades of exhaust tubing out there too. thin wall cheap tube will rust quickly.

I went thru this for years, ripping rusted old exhaust components out, and have to replace them again within 12 months.

I solved it by not being such a tightwad and springing for Stainless components and they have held up for several years without a spec of rust other than 1 weld that was made with a regular steel welding wire.

If I would have had to pay to have corroded parts replaced I would have spent twice what the SS components cost in the first place, sometimes good enough isnt really good enough!

It only ever rusts out at the muffler, where the pipe goes into the muffler seems to rust and pull out.

I'll try a Magnaflow or something with good quality

Thanks

Sounds like a good plan, and they are not that bad cost wise really, 40-50$ or so for a muffler.