MP3s will be the same no matter what software you are using, assuming you are using the same MP3 encoder library (like LAME), same bitrate, etc.
Most internet MP3s are rendered at:
44.1KHz (44100) sample rate
128 KBPS bitrate
CBR
I recommend:
44.1KHz (44100) sample rate
192 KBPS bitrate
CBR
q=0 (quality = 0, or highest, which makes a huge difference)
That is the best compromise between file size and quality. In most stuff I don't hear a difference between 192KBPS and the better 320KBPS, but 320 is much bigger in size.
Edit: Attaching a screenshot of the "recommended" settings. You may want to change Resample mode: to "Better 192" if it takes too long.