The important things to look out for really depend on what you are wanting to vac pack for and how often.
The important things are really sealing width, vacuum achieved, the power of the heat sealer and the duty cycle
- Sealing width - I found that the 30 cm of the Eiffel would do almost all of what I needed - There were a couple of times when I would have liked a larger seal but they were very rare
- Vacuum - Look for one that will do -0.8 Bar to -0.9 Bar. This is not as high as the in the chamber sealers but is good for a side suction unit
- Heat sealer - Along with the thickness/quality of the bag this determines how well the bag will remain sealed. The ideal is to have one that provides a twin heat seal but this is uncommon in this type of packer. Instead you should ensure that the unit can also do "seal only" as this will enable you to add a second seal if required. For thicker bags (e.g. sous vide) you will also need to have a more powerful heat seal.
- Duty cycle - check its usage rating by looking at the product reviews. Some are only designed for casual kitchen use and will overheat if used constantly without being allowed to cool. If you are only planning to seal the odd pack of leftovers this will not matter too much bit if you plan to pack 20 bags of smoked cheese at a time then this is a consideration.
I cannot see the vacuum rating or the sealing capability of the Foodsaver though I expect that they are out there.
For this type of machine you will need the embossed pouches as it is a side suction packer. These are readily available from a number of sources on the net and if you shop around you can get some good deals. When buying though make sure that they are food grade. Many of the really cheap ones on e-bay or Amazon are not.
You really need to get a selection of sizes as you will be packing a lot of different things. This is best achieved by buying the "bags" on a roll as a tube and cutting and sealing them to the desired length as required. If you buy two different width rolls you will be able to create an almost infinite number of bag sizes. Don't forget though that both the Foodsaver and Eiffel Freshpack Pro can handle a maximum width of bag of 11" (28cm) so don't buy rolls or bags that are wider than this. (This may sound obvious but learn from the mistake I made when buying my first stock of bags!)
I mostly used to buy mine from Lava Vacuum Packaging http://www.lava-vacuum-packing.com. At the time they were among the cheapest and the quality of the bags/rolls were good. Usually 90 micron bags will be fine for packing most things but you can also get extra thick 160 micron bags for sharper objects and for a longer packed life..