Batch is almost never a good thing. However, for this use, you'll be fine.
I'd for sure avoid any "online converter", as you have no idea what it's doing in the background. And in almost all cases, it's using default ffmpeg settings, and that's never good.
Avoid all that Chinaware shlock. All those $50-ish programs that claim the moon, but deliver cheese.
If you want to convert to H.264, and batch, then you need to learn Hybrid
. That's very powerful software, sort of an ffmpeg frontend, but so much more. I use that heavily for my hobby projects, which entails encoding and re-encoding H.264 for LAN DNLA streaming.
Selur is a video user, and his site is akin to me having lordsmurf.com
Best of all, it's freeware.
Everything you want can be done in Hybrid, fast (multi-core x64), and with quality.