this is what i use
"C:\Program Files (x86)\Steam\Steam.exe" -silent -nochatui -nofriendsui -console -no-browser
it allows run STEAMclient w/o new UI/chat/friends/popup/browser bloat
(especially those 200+ popups i can't disable about group/friends invites) it's very effective for fast testing (as someone who is game industry it's double important) for advanced gamer it saves some CPU / GPU cycles and some RAM /  VRAM space
even less stressing your SSD 
it avoids the STEAM browser cluttering the disk space with cache growing out of control when i want buy / discuss something i use reliable web browsers 
and when i want to join the chats/friends i just start it w/o those switches there are some more compatibility switches like
-tcp which may help in more firewall strict networked environment