This question will probably not be answered the same way by all prospective builders. In general, however – as a kind of quintessence – I would say that besides the question of purchasing the plot and the associated costs, an increasing level of commitment from the builder is required but also enabled, namely from the developer to the construction manager (not general contractor!) to the architect with individual contracting. (Basically, architect + general contractor is also a conceivable combination.) Which of these suits you best is difficult for us to answer. Generally, it should be noted that the services of a good to very good and above all creative architect become all the more apparent the more complicated the starting situation and/or requirements are, for example “difficult” plot, very restrictive budget, minimal space requirements, etc. It should also be mentioned that there are very good construction managers – typically smaller providers – whose architectural performance is equivalent to that of an independent architect, though this is less the rule. Ultimately, there is still a difference in team membership. The architect plays on your team and will, if necessary, also help you “against” opposing craftsmen. The general contractor/construction manager usually has a stronger bond to “their” craftsmen, which can sometimes lead to a conflict of interest. Furthermore, they will naturally try to carry out the execution as cheaply as possible since the price is fixed from the outset. Developers tend to cover the mass market, which means the individuality of building is reduced in order to achieve the desired economies of scale.
You will find further aspects if you read even more here than before.