i haven't used logic very much, but my main daw is sonar. i absolutely love it. it's cheaper overall, just as powerful, and is extremely fast. for instance, i recently tracked an amazing well known band. im talkin' some of the best musicians in their genre good... they were some hired guns for a larger project. anyway, the arranger and writer of most of the music was working with me, getting some production stuff out of the way, and he says, "you know, when we heard you were using sonar, we were questioning if you were even a serious studio, but now that i've been here for a while and see how it really is, you are making me want to go buy it! we can't believe how much more intuitive it is than pro-tools. it's just so quick, it allows us to create music without the daw getting in the way."
one thing to keep in mind too, is that if a p.c. goes down, you can replace a part very quickly and cheaply...and most computer shops have p.c. parts out the wazoo. if a mac goes down, good luck!
if you do decide to get sonar, i'd say pick sonar producer edition. it's the best!
here's a review:
http://www.musicradar.com/gear/all/comp ... 194/review
with all that said...sonar and logic are just different means to an end. they both have their strengths and weaknesses. it's kind of like comparing a corolla and an accord. they'll both get you to your destination. it just depends on what features you'd like. the only difference, is that to run logic, you gotta spend a whole lot of money on the machine and have only a few options for interfaces, vs. a whole slew of interfaces and a more affordable machine. i own both macs and p.c.'s, and i've had both crash on me. the p.c. i got going within a few hours, whereas the mac, when it went down, it was an invidia video chip on the mother board (or logic board as apple would call it). with the p.c., i was back up and running with just a few moments, where as the mac, it took several days to get the parts in and the motherboard replaced.
in other words, it's not so much of the daw that matters, but rather everything else you have to keep in mind just to get the daw running. if you are going to be a professional studio, you have to keep overhead costs in check. not only today, but in days and years to come.
good luck.