Cheapest and easiest to use, compared to FL studio and Reaper IMO. (I won't by trying the demos of any other DAW's until I have cash for them.) Although a few design choices baffle me - for example - I can't edit midi controllers using an automation track, nor can I apply automation for effects over a SubMix track. I've complained about it on the forms though - fingers crossed for a greatly improved Mixcraft 8?
Admittedly, I'm fairly inexperienced when it comes to mastering, but:
The EZQ Equalizer that comes with Mixcraft is a godsend for simple tone adjustment.
I really like the Parametric EQ 2 that comes with the FL Juice Pack, but there's some free alternatives you can use, like Blue Cat Audio's Triple EQ - only 3 bands though.
LoudMax is a simple limiter that you can get for free. (It has more than 1 knob! It has 2!)