Runtastic + heart rate monitor. Which HRM is best???

Himejii

Ok, I spent most of the day testing out fitness apps for Android (Nexus 5). I have a Polar H7 en route from Amazon, and I have a Garvin Vivofit from Costco. I'm not entirely sold on the Vivofit (seems like a bossy, glorified pedometer) but I'm giving it a week to make up my mind.

So far Runtastic is my top choice. I also tried MapMyFitness and iCardio. These seem to be the top 3 (feel free to suggest your favourite, I haven't committed yet).

My test workouts were a 8km bike ride (25 min) and a 1.5km walk (17 min). Here are the calorie summaries for each app (some entered manually):
MFP: 208 (bike), 78 (walk)
MMF: 315 (bike), 111 (walk)
iCardio: 548 (bike), 149 (walk)
Runtastic: 191 (bike), 85 (walk)

My goal is to have my workouts automatically logged to MFP, so I'm using MFP as a baseline for this test. Clearly Runtastic is the closest. iCardio is basically double, and MMF is also grossly over. That rules them both out. All were done using the same height & weight info (83.5kg, 165cm, female, 32). Since I've heard that MFP over-estimates calories to begin with, I'm assuming that anything that reports even higher is way out. Perhaps they're reporting gross consumption??

Runtastic was pretty easy to use, and it synced instantly with no further action on my part (iCardio needed me to manually sync, and MMF wouldn't sync at all). Runtastic also reported lower than MFP for my bike ride, which is my primary non-gym cardio, and comparable on the walk.

Soooo what's my point? I'd like to keep using Runtastic, and I'm willing to choose whichever heart rate monitor will give me the most accurate results and pair easily with this app. I use Android (Nexus 5).

I've read that the Polar H7 is most recommended HRM's, so I ordered one from Amazon, but now I'm reading that it has trouble pairing with Runtastic, which would make it useless. The reason I chose the H7, however, is that it reportedly does the best estimate of VO2, and the Polar Beat app can supposedly take this entered manually for a more accurate result. But if I'm not using Polar Beat, then that feature is moot, and any decently accurate HRM would do.

I also I know I'm more likely to stick with something if it's über easy to use. And as long as it's not over-reporting calories, I can live with mild inaccuracy. My current take on "eating your exercise calories" is that I'll look at them as a safety net if I'm feeling more hungry from a workout, but I won't automatically eat them just to balance the books. I'll change my approach if that doesn't seem to be working for me.