A good way to compare systems is with a check-list of features. It is best to buy and install one module at a time. The more options the system allows, the better. Your accountant is a good source of computer advice. It should be obvious that a large software company does not guarantee a satisfactory installation.
Some effects are directly contrary.
Since most software companies have a structure composed of few experts and a large supporting cast, you can see that mere size may be of no particular benefit to you. Cost bears no real relationship to quality either. High price may mean nothing more than high overhead and a highly paid sales staff. A large user base is also a two-edged sword. One way to sell a lot of software is to sell a blandly generic package that doesn't do a particularly good job for anyone.