Bill, I did a fair amount of research when buying for my use/garage and let me say first of all I'm a stickler for safety and security with stability in use. Like Richard said, safety locks are a first question to ask followed by are they automatic and easy to use. The drive over type scissor lift Richard shows has all the safety issues covered but in the end I went with the drive on/over platform scissor lift from equipment for garages and for £100 more went with the 3500kg version. The advantage with this type of lift for me was it stays where you put it, need it. and the car at full height is very stable. These two types also allow you to raise the car and when set on the stops you can switch it all off and happily leave the car for extended periods when long jobs are being undertaken. I have limited space where I keep my lift and I wanted ease of use and minimum hinderance when not needed.
There will be choices in what you require in use and within your budget but when you think you have made your choice, again look very closely at what it is that you are considering buying. I think I probably started with a price in mind that I wanted to spend, but in the end it was all the things that you should look at that made my mind up and I ended up spending about double what I had originally hoped to spend. I don't regret it after having used it now for some time. I really enjoy working safely on the cars knowing that both the car and myself are being looked after!
I don't know where you are based but if you are near or ever get to North Wales, not too far from Chester PM me and you are welcome to come and have a play with my lift. Failing that there are some really good Video's on youtube showing function of the various types and makes! Martin.