I am as severely allergic to mosquito bites as it gets. I have a prescription steroid cream I have to use for bites and yes, sometimes I have to go to the hospital to get shots because my face swells up. And of course, those of us with the worst allergies to them attract them all the more.
The SkeeterVac is useless for someone like me. I haven't tried the Flowtron, but it's looks similar to the Mosquito Magnet, which I do have. I can tell you that the Mosquito Magnet works wonders! We have a couple acres of wooded property with a creek running through the woods, so we have our fair share of skeeters. The mosquito magnet covers a 500 yard radius (depending on the model you get) and in the 5 years since we've had it I've seen maybe 3 mosquitoes. The darn thing was expensive but for me it was probably just as good an investment as our house! It uses a propane tank which needs replacing about once a month (only during the summer though) and also uses bait which is easily found at Lowes or Home Depot or even WalMart and is inexpensive and doesn't need to be replaced very often at all (I think we've replaced it maybe 2 or 3 times in 5 years). Also, we haven't had any problems with attracting more mosquitoes from our neighbors' yards, but it even seems to have helped our neighbors out some. It said it has a 500 yard radius, but I think it works well beyond that.
So, if you're really willing to make an investment, the Mosquito Magnet is well worth it. I normally would never set foot out in our yard, but the mosquito magnet works so well we decided to build a huge deck onto the house and I spend most of my day on it everyday. I feel like I got my life back because of it.