I would avoid Tiger Direct like the plague. When they send exactly what you ordered, you can get some very good deals from them. But if anything at all goes wrong, their customer service is legendarily bad. They'll stall, delay, bluff, refuse to send an RMA, then delay some more... until the time window for returns/refunds has expired and they tell you "too bad, sucker!"
A handy technique is to google for the name of a retailer plus the word "complaints":
"tiger direct" complaints
The search above reveals a plethora (yes, an entire plethora) of gripes. Top on the list:
Consumer complaints about Tiger Direct at consumeraffairs.com
Read that page and you'll see the kind of sleazy tricks Tiger Direct have been pulling for years without cleaning up their act. If that's not warning enough, check out some of the other links Google turns up.
Could be that the other companies you list have similarly low reputations. Google them too and find out what previous customers have gone through. Note that ANY large retailer is going to have some complaints! Dig a little to see whether they're for isolated instances or they indicate a regular pattern of unacceptable business practices (Tiger Direct definitely fits the latter).
Hope this helps you to avoid grief!
Meffy Ellis