I'm a fan of the capture card option. I use one of the USB options that Pinnacle offers and Even use their software at times. Its just fine if you don't have a lot of post editing to do. Occasionally, I'll flip over to the MAC side, but only when a lot of editing is necessary.
Honestly, your biggest factor is what kind of quality you need. There are Processor Amps that can really help you get great quality, but if this isn't an absolute priority, then straight from VCR to capture is fine. Be sure to scale back the sharpness of the VCR when playing, MPEG handles the softer video a little better. Also consider using a half-res rip (pinnacle supports this) to fit more video per DVD. My family used to record using SLP that supports 6 hours of video. A full resolution rip of these tapes would require almost 4 DVD's. Half res solves this issue and cuts way back on the time of authoring. Figure 2 total hours for every hour of video you want converted if you have a decent PC. Depending on what your time is worth, and how fast you need it done, converting 20 commercially might be a better option. Have you priced it out?