The Matrox MXO2 Mini MAX is a professional capture and playback/monitoring device, that also has hardware-based H.264 encoding included (MAX model only). Once you capture the footage, export with Adobe Media Encoder and MXO2 MAX provides hardware-accelerated H.264 encoding. Or just get MXO2 Mini (without MAX) for capture, and let AME do the H.264 encode via CPU, but that can take much longer depending how fast the Mac is.
Note that the MXO2 needs a stable signal to capture. If the source tape is bad, MXO2 may not record. I'd recommend a deck with built-in TBC, such as many of the prosumer S-VHS decks feature, to stabilize the video signal. If you have a cheap old standard VHS deck and marginal tapes (jumpy playback), you could have capture issues.
MXO2 can be purchased with choice of 3 interface adapters - PCIe (desktop), ExpressCard34 (laptop), or Thunderbolt (newer Macs), so can work with most Macs or PCs that way.
Safe Harbor Computers
If you are going to edit the caputered footage, H264 is not a good choice (highly compressed).
Mov as you are on a Mac would be a better choice.