I think there are 3 main factors when reviewing a pump.
- Valve connection method, clamp/screw.
- Valve support (not every pump supports both types of bike valve, but most do)
- How high a pressure tire do you need? (some road bikes need really high, > 100 psi).
A lot of modern pumps use a clamp to secure to the valve. These tend to be awkward when you're completely flat and quite challenging to pump assuming there is no hose between the pump and the clamp because you have to keep the pump rigid while pumping to prevent the connection being broken. I personally favour the more old fashioned way of having a screw on hose. There are some manufacturers who still do them. They're also less likely to break off under high pressure.
There are some extra requirements that might be important to you.
- Bike fitting (may not be that important)
- Extra features - some contain compartments for puncture repair patches
- Ease of pumping - pumps will push in different amounts of air per stroke so some are easy but take a long time to pump up.
I have a good bike fitting for my pump but I don't use it on commutes because it's simpler to keep my pump in a pocket on my bag.
Once you've found one that looks like it meets your requirements check out the reviews on the bike shopping sites. They should warn you of potential downfalls with the products. You might also want to see if your local bike shop can let you try out a demo. Do it from flat on your own bike because that will give you the most realistic test of a pump. Pumping an already inflated tire is too easy.
As far as practical recommendations go I personally recommend the small pumps from Lezyne. (I would link to their own site but it's all flash.)