In my opinion, Polar is definitely the way to go. I spent a few months researching HRMs before deciding that Polar got you the most bang for your buck. I ended up purchasing an F11 on ebay and then the WearLink transmitter (much better than the plastic one) at all3sports.com (with coupon). I feel like I got an excellent deal.
Now that I've had the monitor for a few months, I can tell you that I like the OwnZone capability (you set your own heartrate targets by actually walking/running while it records you at different intervals) as well as the OwnCal (it calculates the calories expended based on your height, weight, age and sex). I don't care about the ability to export to my computer like I thought I would (especially now, with traineo to track my info).
Polar works very well in the gym--I've never had a problem with the machines reading my heart rate from the polar transmitter. And, they say that using the "coded" wearlink transmitter means that you won't pick up someone else's info. Even when I wasn't using a coded transmitter, I don't think I ever picked up other biorhythms.
Re: body fat analyzer. See Ron's post.