If you have a local craft store or two look to see if they are demoing any of the machines or see if a friend has one. You'll get a lot of different opinions as we all have our own criterias as to what we like and don't like. Another thing you can look for is if you have and craft conventions nearby like Creaking Keepsakes as an example. At a Creating Keepsakes convention they usually have all the major vendors there that you can see and try the machines from the cricut, wizard, sizzix and cuttlebug. I've attending the CKC in Valley Forge PA the last 4-5 years and they are always there.
Each die cutting machine has their pros and cons. Most of them will take each other dies however there are some exceptions. Sizzix steel rule dies will cut up to 3 pieces of cards in one cut. It will also cut material, felt and other materials. That can be a plus if you are doing in bulk. Personally I own the original Sizzix red, a Sizzix Sidekick and a Elliston/Sizzix Big Shot. I've used a sizzix big kick, cuttlebug and wizard before but prefer the Big Shot but that's my preference. It all depends on what you want to do with it. I can tell you sizzix.com has some great Clearance items on sale right now. The prices have been that way the last 2-3 weeks. BIGZ dies originally $19.99 for $4, Sizzlit Decorative strips originally $19.99 for $4 and such. scrapbookingalley.com has good prices on spellbinder dies and okay prices on sizzix/cuttlebug. scrapyland.com has run some good sales in the past on sizzix, spellbinders and especially quickutz. Occasionally you can find good deals and sales on overstock.com, scrap-mart.com, ohmycrafts.com (pre orders can be slow but I always got what I ordered), joann.com (sign up for sales and look for free shipping coupon codes) and of course sizzix.com. I've shopped at all sites I've mentioned with no issues.
If you go the sizzix, cuttlebug or spellbinder route on the plus side you can pick up a lot of the basics if you have a Joann, ACMoore, Michaels or Hobby Lobby near using 40-50% off coupons.
Good luck with your decision. Karen