Do you mean, what is the best software used to compress with? You're probably using Compressor, are you exporting directly from the timeline? The problem with Sorenson 3 is that the version that comes bundled with most software applications is not nearly as good as the standalone version you have to pay for separately, but the standalone version is very good! If you've just starting out compressing files, I would stick with the basic presets, see what those give you, (Pixelization Vs. File size) and try to stick with the presets that allow for streaming your video. Then, once you get a good handle on how it all works, try messing with the settings.... It takes a long time, sometimes, to get the results you want.
I don't know how long your reel is, so that may be a reasonable size if you have a 3 minute reel
My reel is 1 minute, and I don't feel comfortable compressing it any lower than 9.4 mb simply because I want to retain as much quality as I can, and it streams fine.
Assuming this is for your website:
The settings I find work well from Premiere, are Sorensen 3, with around 30% quality, 30kbs bit rate, 24 fps, 400x300 (I've heard that ratios that are divisible by 4 compress better for some reason). Turn on the compress header, and prepare for web streaming
QDesign seems like a good sound compression... I compress sound as low as it goes... but it doesn't seem to save that much in file size.
The quality, and bit rate could go down, as could the proportions if you wanted to offer a high/low quality option for downloading/streaming