Do a search on this site on your topic. This has been discussed quite extensivly in the past. They both have there goods and bad and it all depends on what you want to do.
I use STAAD Pro 2004 for stair and platform design. I've been happy with it. It's quite user friendly and been easy to pick up the features. My only complaint is REI's technical support which has been inconsistent.
STAAD Pro 2004 designs per 9th Ed. ASD; 2nd & 3rd Eds. LFRD; ACI-318 2002 & 1999 Eds; 1985 & 1994 AITC (Timber). It can also design per AASHTO and Am. Cold Formed Steel Code (1996).
It also has UBC-85, 94 & 97 as well as IBC-2000/2003 seismic load generators, and ASCE 7 (-95?)Wind Load Generators.
I'm not sure what 2005 STAAD Pro's design parameters are. Check out reiusa.com
I think STAAD is the standard engineering analysis tool in the industry. Every software has good and bad. We don't use STAAD for timber design (we use WoodWorks). We don't use RISA anymore since it is more redundant. STAAD is very flexible and it's multi-material support (concrete + steel) is really good. They have been around much longer so they have had times to fix their kinks. RISA's concrete was just recently introduced and I was told by other's that is still in beta mode.
