Well... this is a VERY loaded question as most people will have different opinions.
That said...
The Directv D-10 works great. Downside is that the Menu is a bit small.
The hughes Receivers work good but are being phased out.
If you want a DVR go with the R10 its much improved over its predacessors.
As For dealing with... there are 3 good routes IMO
1. ValueElectronics (10% Satelliteguys Discount) Link at top of every page
2. Local Dealer Some are good some are bad, most will sell you what you need
3. Direct From D* they will send you whatever they feel like.
Ive dealt with VE several times and every time they have been respectable and have dne what is needed to get the job done.
Now as for speed in channel changing. You really wont find much difference in the basic receivers (new ones) because it takes a coupel of seconds for the receiver to send out the signal and locate the correct frequency then start decoding it. Average Channel change time is 2 seconds. This is why the EPG is there.
If you want a DVR expect Channel change times of up to 5 seconds. this is so the DVR can start buffering the signal.
hope this helps.