Picking an antibody supplier is tricky, however the quality can vary greatly between antibodies from the same supplier. What is your protein target?
I would recommend that you find a paper that has used an antibody that is specific for your target in your species and/or application. This will give you an indication of it's specificity and quality.
Keep in mind that many companies carry the same monoclonal antibody clones, so you can shop around a bit between companies once you have a specific antibody in mind to find the best price and customer service. Also many of the big antibody companies buy and resell antibodies from other suppliers under their own name. Often you will pay more for less of the same antibody when you purchase through a large supplier versus a small company. Small companies also tend to be the original manufacturers of the antibodies, so they are better at providing technical support.
A few companies, including StressMarq Biosciences, offer an antibody trial program where you can try a sample size for free or a low price. This enables you to test it out before you invest in the full size vial. Here's a link to our trial program page. We are able to offer a sample size of nearly any antibody in our portfolio.